SPECIFIC AND NON-SPECIFIC POLYSACCHARIDES OF TYPE IV PNEUMOCOCCUS

1. Three nitrogen-containing polysaccharides have been isolated from autolyzed cultures of Type IV pneumococcus: (1) a type-specific carbohydrate differing markedly from those of Type I, II, and III pneumococcus, and representing a type of substance hitherto not observed among specific polysaccharides, (2) a chemically similar carbohydrate without specific function, and (3) the "C" substance, or species-specific polysaccharide of Tillett, Goebel, and Avery. 2. The chemical differences between the specific polysaccharides of Pneumococcus are discussed, and the relationship of the new examples to chitin is pointed out and its bearing indicated on the unsettled controversy as to whether or not chitin occurs in bacteria. 3. The data of Tillett, Goebel, and Avery on the "C" substance have been extended.

PROTEIN FRACTIONS OF A SCARLATINAL STRAIN OF STREPTOCOCCUS HEMOLYTICUS

1. A tentative method is described for extracting a labile nucleo-protein from scarlatinal Streptococcus hemolyticus. 2. The product differs chemically and serologically from the fractions prepared by subsequent alkaline extraction of the cell residues, and from protein obtained by the classical method for extraction of bacterial "nucleoproteins." 3. The new nucleoprotein is sensitive to very weak alkalies and readily loses nucleic acid under these conditions. The protein degradation products resemble the alkaline-extracted protein fractions of the cell residues. 4. The bearing of the properties of the new nucleoprotein on the chemistry of nucleoproteins in general is discussed, also the possible relation of the fractions obtained to the analysis of streptococcus antigens made by Lancefield.

THE SOLUBLE SPECIFIC SUBSTANCE OF PNEUMOCOCCUS : THIRD PAPER

1. Refinements in the methods for the isolation of the soluble specific substances of Types II and III pneumococcus are described. These improvements have resulted in the isolation of the end-products in a form free from nitrogen and of enhanced activity with immune serum. 2. The soluble specific substance of Type I pneumococcus is described and shown to differ sharply from the corresponding substances of the other two types, each of which, in turn, differs from the other. 3. Progress is reported on the identification of the sugar units from which the polysaccharides are built up. 4. The evidence so far accumulated is believed to favor strongly the view that the polysaccharides isolated are the actual specific substances of Pneumococcus.

QUANTITATIVE STUDIES ON THE PRECIPITIN REACTION : EFFECT OF SALTS ON THE REACTION

1. A quantitative study has been made of the effect on the precipitin reaction between the specific polysaccharide of Type III pneumococcus and the homologous antibody of salt concentrations ranging from O.1 M to 1.79 M, including the effect of ions of higher valence. 2. Within these limits, observed decreases in precipitated antibody with increasing salt concentration appear to be due to a decrease in the amount of antibody combined with the S III, rather than to an increase in solubility of the S III-antibody compounds. 3. The egg albumin-antibody reaction is far less sensitive to changes in salt concentration than is the S III-antibody reaction.

CHEMICAL STUDIES ON BACTERIAL AGGLUTINATION : II. THE IDENTITY OF PRECIPITIN AND AGGLUTININ

1. The absolute, quantitative agglutinin method has been used for the determination of the presence or absence of small amounts of specific polysaccharide in pneumococcus variants. 2. A technique is described for the removal of group specific antibody from antipneumococcus horse serum. 3. The type specific anticarbohydrate agglutinin and precipitin are not only present in identical amounts in Type I antipneumococcus horse serum, but a reduction in one is also accompanied by a quantitatively identical reduction in the other, providing evidence for their actual identity. In purified antibody solutions somewhat more agglutinin than precipitin is found, possibly owing to alteration of a portion of the antibody in the process of purification.

THE PRECIPITIN REACTION BETWEEN TYPE III PNEUMOCOCCUS POLYSACCHARIDE AND HOMOLOGOUS ANTIBODY : III. A QUANTITATIVE STUDY AND A THEORY OF THE REACTION MECHANISM

The precipitin reaction between the specific polysaccharide of Type III pneumococcus and homologous antibody formed in the horse can be accounted for quantitatively by assuming the chemical combination of the components in a bimolecular reaction, followed by a series of competing bimolecular reactions which depend upon the relative proportions of the components. These reactions would lead to the formation of larger and larger aggregates until precipitation ultimately occurred. The mathematical formulation of this theory on the basis of the mass law is described. The derived expressions are shown to be in accord with the experimental findings and the constants used in these expressions are shown to have definite significance. In spite of the wide variation in the properties of individual sera these expressions permit the complete description of the behavior of an unknown serum with S III without an unduly burdensome number of analyses. The quantitative theory presented has been found applicable to other instances of the precipitin reaction, as will be shown in subsequent papers.

QUANTITATIVE CHEMICAL STUDIES ON COMPLEMENT OR ALEXIN : I. A METHOD

1. A quantitative micro method, conforming to the criteria of analytical chemistry, is proposed for the estimation of complement, or its combining component or components, in milligrams per milliliter instead of in the customary relative and variable volume units. 2. Data are given showing the range of accuracy and reproducibility of the new method.

A "SOLUBLE SPECIFIC SUBSTANCE" DERIVED FROM GUM ARABIC

1. By partial acid hydrolysis a specific carbohydrate may be isolated from gum arabic (gum acacia). This carbohydrate is comparable in its precipitating activity for Type II (and Type III) antipneumococcus serum with the bacterial soluble specific substances themselves. 2. On hydrolysis this fraction yields galactose and two or more complex sugar acids, one of which appears to be a disaccharide add comparable with those isolated from the specific polysaccharides of the Type III pneumococcus and the Type A Friedländer bacillus. 3. The significance of these findings is discussed.

THE SPECIFIC POLYSACCHARIDES OF TYPES I, II, AND III PNEUMOCOCCUS : A REVISION OF METHODS AND DATA

1. The thermolability of the specific polysaccharides of Types I, II, and III pneumococcus has been shown by three independent methods: (a) diminution of the viscosity of solutions on heating; (b) decrease in the amount of antibody precipitated from homologous rabbit antisera; and (c) increased tendency (S III) to pass through a collodion membrane. 2. These effects may be explained most simply as a partial depolymerization under the influence of heat. In air, particularly in the presence of broth, oxidation also appears to be involved. 3. Improved and simpler methods of preparation based on these findings, are given for S I, S II, and S III. The resulting products precipitate more anti-S from homologous rabbit antisera than do the earlier preparations. 4. The methyl glycoside of methyl galacturonate has been isolated from the hydrolytic products of S I, and evidence of the ultimate structural unit obtained.

THE SOLUBLE SPECIFIC SUBSTANCE OF FRIEDLANDER'S BACILLUS : PAPER II. CHEMICAL AND IMMUNOLOGICAL RELATIONSHIPS OF PNEUMOCOCCUS TYPE II AND OF A STRAIN OF FRIEDLANDER'S BACILLUS

The chemical and immunological properties of the soluble specific substances of a strain of Friedländer's bacillus and Pneumococcus Type II are described and correlated, and the serological and antigenic similarity of these biologically unrelated organisms is discussed as an example of heterogenetic specificity among bacteria.

THE ACTIVATING EFFECT OF MAGNESIUM AND OTHER CATIONS ON THE HEMOLYTIC FUNCTION OF COMPLEMENT

1. The evidence presented indicates that Mg⁺⁺, or other cation such as Ca⁺⁺, Ni⁺⁺, or Co⁺⁺, is essential for the hemolytic action of C'. Ca⁺⁺, Ni⁺⁺, and Co⁺⁺ are less effective than Mg⁺⁺. The hemolytic system usually does not contain sufficient Mg⁺⁺ for optimal hemolytic activity so that a marked enhancement can be obtained by addition of extra Mg⁺⁺. 2. The enhancing action of tissue fluids can be ascribed to their contribution of Mg⁺⁺. 3. Substances which bind Mg⁺⁺ and Ca⁺⁺ are anticomplementary when added to the usual hemolytic system which contains only a small quantity of Mg⁺⁺. This type of anticomplementary effect can be overcome by addition of extra Mg⁺⁺. 4. Ca⁺⁺ may also be essential to the lytic process but its action is much less pronounced than that of Mg⁺⁺.

THE MOLECULAR WEIGHT OF ANTIBODIES

1. Highly purified rabbit Type III pneumococcus anticarbohydrate proved to be homogeneous in the ultracentrifuge and its sedimentation constant, 7.0·10^–13, did not differ from that of the principal component of normal rabbit globulin or of immune rabbit globulin containing up to 50 per cent of anti-egg albumin. The molecular weight of antibody in the rabbit is therefore probably very close to that of the principal normal globulin component, namely, 150,000. 2. Highly purified horse Type I pneumococcus anticarbohydrate, on the other hand, was only homogeneous in the ultracentrifuge when prepared from sera stored without preservative. Its sedimentation constant, 18.4·10^–13, coincided with that of the principal globulin component in most of the Felton solutions and purified antibody solutions studied. The molecular weight of pneumococcus anticarbohydrate in the horse is probably three to four times that of the principal normal globulin component. 3. The significance of the differences between pneumococcus anticarbohydrate formed in the rabbit and in the horse is discussed. 4. Results are given of ultracentrifuge studies on the molecular species in solutions of egg albumin-anti-egg albumin specific precipitates dissolved in excess egg albumin. The implications of the results are discussed.

A QUANTITATIVE STUDY OF THE PRECIPITIN REACTION BETWEEN TYPE III PNEUMOCOCCUS POLYSACCHARIDE AND PURIFIED HOMOLOGOUS ANTIBODY

1. A quantitative study of the reaction between the soluble specific substance of Type III pneumococcus and its homologous antibody has been made. 2. The entire reaction, from excess of antibody, to excess of specific substance with its accompanying inhibition zone effect, may be expressed by three mass-law equations. 3. The significance of these findings is discussed.

QUANTITATIVE CHEMICAL STUDIES ON COMPLEMENT OR ALEXIN : II. THE INTERRELATION OF COMPLEMENT WITH ANTIGEN-ANTIBODY COMPOUNDS AND WITH SENSITIZED RED CELLS

1. The molecular quantities of hemolysin and complement combining component or components (C'1) involved in hemolysis have been calculated on the basis of new, quantitative, absolute methods of analysis. 2. Molecular combining ratios between antigen, antibody, and C'1 have been established. 3. The data are shown to be in accord with the theory of combination of multivalent antigen with multivalent antibody. 4. The fixation of complement by antigen-antibody combination is qualitatively and quantitatively accounted for on this basis.

ANTIBODY FORMATION IN MEN FOLLOWING INJECTION OF FOUR TYPE-SPECIFIC POLYSACCHARIDES OF PNEUMOCOCCUS

1. Random selections of the sera of trainees injected 2 months previously with the specific polysaccharides of Types I, II, V, and VII pneumococci contained quantities of antibody to Types I, II, and VII sufficient to account for the favorable results of the immunization procedure. 2. As in earlier studies, the levels of the antibody for the C polysaccharide remained relatively constant before and after the injections. 3. The serum from the preliminary bleedings often contained antibody to the Type VII polysaccharide. This remained relatively constant in a control group injected with saline.

IMMUNOLOGICAL RELATIONSHIPS OF CELL CONSTITUENTS OF PNEUMOCOCCUS : SECOND PAPER

In this paper the general immunological significance of the intact pneumococcus cell and of its protein and carbohydrate components is discussed.

THE SOLUBLE SPECIFIC SUBSTANCE OF PNEUMOCOCCUS : SECOND PAPER

1. The method for the concentration and purification of the soluble specific substance of Pneumococcus has been improved. 2. Highly purified specific substance of Type II pneumococcus of polysaccharide nature is shown to be recovered essentially unchanged after precipitation by immune serum, by uranyl nitrate, by basic lead acetate, or by safranine. 3. Marked chemical differences are shown to exist between the specific substances of Type II and Type III pneumococcus, although both react as polysaccharides. 4. The weight of evidence is considered to be in favor of the view that the specific substances of Pneumococcus Types II and III are actually polysaccharide derivatives. 5. The immunological significance of the foregoing view is discussed.

A QUANTITATIVE THEORY OF THE PRECIPITIN REACTION : IV. THE REACTION OF PNEUMOCOCCUS SPECIFIC POLYSACCHARIDES WITH HOMOLOGOUS RABBIT ANTISERA

1. The reaction between the specific polysaccharide of Type III pneumococcus and homologous antibody in rabbit sera is quantitatively accounted for by expressions similar to those derived from the mass law for the corresponding horse sera. Preliminary data are also given for the Type I reaction. 2. Differences and similarities of the reaction with antibodies produced by the two animals are discussed. 3. Calculations are made of the equivalent composition of the specific precipitate at various reference points in the reaction range. 4. Certain theoretical and practical implications of the findings are pointed out.

STUDIES ON THE PRECIPITIN REACTION : PRECIPITATING HAPTENS; SPECIES DIFFERENCES IN ANTIBODIES

1. Partial hydrolysis products of the specific polysaccharide of Type III pneumococcus ranging from 550 to 1,800 in formula weight can be quantitatively freed from unhydrolyzed polysaccharide. 2. The fractions yield specific precipitates with Type III antipneumococcus horse serum but fail to precipitate homologous rabbit antisera, giving rise only to specific inhibition. The aldobionic acid, the structural unit of S III, does not precipitate antisera. 3. A possible explanation and a possible application of the findings are pointed out.

ON THE ANTIGENIC PROPERTIES OF HEMOGLOBIN

Sera produced by immunization with crystalline oxyhemoglobin react species-specifically with hemoglobin solutions. Evidence is presented that in this reaction the hemoglobin itself is the active substance. Conversion of oxyhemoglobin into methemoglobin, carbon-monoxy hemoglobin, or cyanhemoglobin does not alter the response to the precipitating immune serum. Not only the hemoglobin of homologous species, but also that of other species causes inhibition in greater or less degree of the precipitin reaction.

QUANTITATIVE STUDIES ON THE PRECIPITIN REACTION : THE ROLE OF MULTIPLE REACTIVE GROUPS IN ANTIGEN-ANTIBODY UNION AS ILLUSTRATED BY AN INSTANCE OF CROSS-PRECIPITATION

1. Antisera to R-salt-azo-benzidine-azo-crystalline egg albumin give precipitates with crystalline egg albumin by virtue of their antidye content. 2. The quantitative course of the reactions with increasing amounts of antigen is very similar for the dye-antidye and egg albumin-anti-egg albumin systems, but differs markedly for the cross reaction between egg albumin and antidye. 3. A possible explanation for the occurrence of this one-sided crossreaction is given in terms of reactive groupings on the antigen and antibody. 4. A qualitative expression of the course of the cross-reaction is given in terms of the laws of classical chemistry.

A QUANTITATIVE THEORY OF THE PRECIPITIN REACTION : II. A STUDY OF AN AZOPROTEIN-ANTIBODY SYSTEM

1. A quantitative theory of the precipitin reaction based on the laws of classical chemistry has been tested on an azoprotein-antiprotein system and found to apply. 2. With its aid relationships may be deduced which permit the calculation of the behavior of an antidye serum over its entire range after a few quantitative chemical analyses have been made for antigen and antibody in the precipitate. 3. An empirical relation is also presented which further reduces the number of analyses necessary. 4. A study of supernatants in the inhibition zone has shown that the entire amount of dissolved antigen-antibody compound present is precipitated when supernatants are analyzed for antigen by the precipitin method.

QUANTITATIVE CHEMICAL STUDIES ON HEMOLYSINS : I. THE ESTIMATION OF TOTAL ANTIBODY IN ANTISERA TO SHEEP ERYTHROCYTES AND STROMATA

1. Total antibody in hemolysins may be estimated from the nitrogen added to sheep stromata suspensions. 2. The method is applied to a number of hemolysins and a correlation, valid to within 20 per cent, established between hemolytic titer and total antibody. 3. When stromata combine with antibody in the presence of guinea pig complement they may take up at least 80 per cent of their weight of complement combining component(s).

THE BACTERICIDAL PROPERTIES OF THE QUATERNARY SALTS OF HEXAMETHYLENETETRAMINE : II. THE RELATION BETWEEN CONSTITUTION AND BACTERICIDAL ACTION IN THE SUBSTITUTED BENZYLHEXAMETHYLENETETRAMINIUM SALTS

By the addition of substituted benzyl halides to hexamethylenetetramine, a series of quaternary salts of this base was obtained. These salts represent a new group of organic bactericides. The results obtained in the tests with these substances upon Bacillus typhosus have demonstrated the existence of direct relationships between chemical constitution and bactericidal action within the series. The bactericidal character is directly attributable to the presence of the hexamethylenetetramine nucleus. The degree of the bactericidal action, however, is determined by the position, character, and number of the groups substituted in the benzene nucleus. By the introduction of the methyl, chlorine, bromine, iodine, cyano, and nitro groups into the benzene nucleus of the parent benzyl hexamethylenetetraminium salt, the bactericidal power of this compound was notably enhanced. The substitution of these groups in the ortho position almost invariably resulted in substances which were more active than their meta or para isomers. The introduction of the methoxy group was without marked effect. Several substances in which two hexamethylenetetraminium side-chains occurred were found to be the most active of the substances of this series when tested against Bacillus typhosus. Comparative tests with other bacterial types demonstrated that these compounds possessed a marked degree of specificity for Bacillus typhosus.

THE BACTERICIDAL PROPERTIES OF THE QUATERNARY SALTS OF HEXAMETHYLENETETRAMINE : III. THE RELATION BETWEEN CONSTITUTION AND BACTERICIDAL ACTION IN THE QUATERNARY SALTS OBTAINED FROM HALOGENACETYL COMPOUNDS

The extension of the study of the quaternary salts of hexamethylenetetramine to those obtained by the addition of this base to the most varied types of substances containing aliphatically bound halogen has demonstrated that the introduction of the hexamethylenetetramine nucleus in this manner results in the production of bactericidal substances or enhances the bactericidal action if already present. In particular it was found possible by the use of the halogenacetyl group, XCH₂CO, as a connecting link, to furnish primary and secondary aliphatic and aromatic amines, alcohols, and hydrocarbons of the most varied character with the hexamethylenetetramine molecule and to study the relation between chemical constitution and bactericidal action in the series of substances so prepared. Because of the variety of chemical types studied, the results are too involved for a detailed summary here. Many of the substances were found to be very powerful bactericides, and in a number of instances derivatives of purely aliphatic nature were found to possess an unusual bactericidal power. Bacillus typhosus, streptococcus, meningococcus, and gonococcus were the microorganisms used for the tests, and striking instances of partial specificity were observed. This specificity was found to favor not one species alone, but instances were found in which each of the types of bacilli was shown to be especially susceptible to one or another of the particular types of compound employed. The source of this partial specificity is to be sought not in the hexamethylenetetramine nucleus itself but in the molecule to which it is attached. The action of some of the substances was tested in the presence of serum or protein and was found to be not at all or only slightly inhibited. In other cases marked inhibition occurred. The factors controlling the serum- or protein-compatibility of these substances are likewise to be sought in that portion of the molecule other than the hexamethylenetetramine.

QUANTITATIVE STUDIES ON THE PRECIPITIN REACTION : THE DETERMINATION OF SMALL AMOUNTS OF A SPECIFIC POLYSACCHARIDE

A method, based on the precipitin reaction, is given for the micro determination of the specific polysaccharide of Type III pneumococcus. As little as 0.01 mg. of S III can be determined. The method should be applicable to any specific polysaccharide upon standardization of an homologous antibody solution or antiserum in the region of excess antibody.

CHEMICAL STUDIES ON BACTERIAL AGGLUTINATION : I. A METHOD

1. A method, conforming to the criteria of quantitative analytical chemistry, is described for the estimation of the agglutinin content of antisera. Examples are given of the application of the method to various antipneumococcus sera. 2. This new, absolute method is discussed with regard to its relation to the commonly used relative methods.

A COMPARISON OF HUMAN AND GUINEA PIG COMPLEMENTS AND THEIR COMPONENT FRACTIONS

1. Defects in methods previously proposed for the estimation of complement components are: failure to ensure an excess of the desired components and failure to ensure absence of anticomplementary effects in the dilution ranges used. Existing data are therefore subject to these uncertainties. 2. Methods are proposed for controlling the adequacy of the reagent for each component, for using it in dilutions below its anticomplementary range, and for reinforcing it with necessary components if these are present in inadequate amounts. 3. Titrations are given of the four components in human and guinea pig complements and in "midpiece," "endpiece," and in the various reagents used, including one with C'3 reactivity, solely, and one withC'4 reactivity. 4. C'3 is shown to be the component which usually limits the titer in guinea pig complement, and C'2 the component of lowest titer in human complement. 5. In immune hemolysis, each component of human complement may be replaced by the corresponding component of guinea pig complement and vice versa.

IMPROVED METHODS FOR THE PREPARATION OF THE SPECIFIC POLYSACCHARIDES OF PNEUMOCOCCUS

The specific polysaccharides of Types I and V pneumococcus give sharp equivalence zones and show maximal precipitation with homologous rabbit antisera only when carefully prepared from cultures which have not been neutralized with alkali. The precipitating power of S V toward homologous rabbit antiserum falls off in 0.1 N NaOH even more rapidly than that of S I, dropping to 7 per cent of the original value in 6 days at room temperature. The alkaline solution develops a large absorption peak at 270 mµ. Directions are given for the preparation of S VII and S XII.

THE PRECIPITIN REACTION BETWEEN TYPE III PNEUMOCOCCUS POLYSACCHARIDE AND HOMOLOGOUS ANTIBODY : II. CONDITIONS FOR QUANTITATIVE PRECIPITATION OF ANTIBODY IN HORSE SERA

The experiments recorded above show that in the case of antipneumococcus horse serum or purified antibody the arbitrary immunological procedure (37 degrees for 2 hours, overnight in the ice box) does not permit either the establishment of a true equilibrium or the precipitation of the maximum amount of antibody nitrogen. Analyses of such horse sera for antibody content should therefore be carried out at 0 degrees and the determinations should be allowed to stand in the cold for at least 24 hours in order to insure the completion of the reaction. It is believed that the similarity of the nitrogen: S III ratios in the specific precipitate, whether obtained from whole serum or from purified antibody, and the failure of added serum to influence the amount of nitrogen precipitated show that the absolute chemical method for the estimation of antibody actually measures antibody and not antibody plus a more or less indefinite amount of non-specific protein. An objection to the use of the method is thus shown to be unfounded.

A QUANTITATIVE STUDY OF THE CROSS REACTION OF TYPES III AND VIII PNEUMOCOCCI IN HORSE AND RABBIT ANTISERA

1. A preparation of the specific polysaccharide of Type VIII pneumococcus is described in which the use of heat, strong acid, and alkali were avoided. 2. Quantitative estimations are given of the homologous and cross reacting precipitin and agglutinin in Types III and VIII antisera produced in the rabbit and in the horse. Quantitative data are also given on the mechanism of the Type VIII precipitin reaction and the cross reaction between the Type III polysaccharide and Type VIII antipneumococcus horse serum. 3. The significance of the data is discussed.

CHEMICAL STUDIES ON BACTERIAL AGGLUTINATION : III. A REACTION MECHANISM AND A QUANTITATIVE THEORY

1. By the application of an absolute, quantitative microchemical method for the estimation of agglutinins, precise data have been obtained on the course of the agglutination of Type I pneumococcus by homologous anticarbohydrate. 2. Within the limitations imposed by the necessity for the agglutination reaction to take place at the bacterial surface, the reaction is shown to be analogous to the precipitin reaction and subject to the same laws. 3. The entire process of a typical instance of specific bacterial agglutination has been quantitatively accounted for on a purely chemical basis and expressed in the form of equations derived from the law of mass action. 4. Experimental verification of predictions based on the theory has shown a fundamental difference between this instance of specific bacterial agglutination and the commonly adduced analogies, and necessitated a revision of current conceptions regarding the rôle of electrolytes and of physical forces in the reaction.

QUANTITATIVE CHEMICAL STUDIES ON COMPLEMENT OR ALEXIN : III. UPTAKE OF COMPLEMENT NITROGEN UNDER VARYING EXPERIMENTAL CONDITIONS

1. Quantitative data are given on the effect of variations in the time of contact and the proportions of the reactants on the quantity of complement combining component nitrogen (C'1 N) found in active guinea pig serum. 2. C'1 N was the same when determined with precipitates containing excess antibody or excess antigen. 3. Finely divided specific precipitates took up the complement combining component (C'1) from subsequently added guinea pig serum almost as well as specific precipitates formed in the presence of complement.

QUANTITATIVE CHEMICAL STUDIES ON COMPLEMENT OR ALEXIN : IV. ADDITION OF HUMAN COMPLEMENT TO SPECIFIC PRECIPITATES

1. A modified method is given for the titration of human complement so that C'1 titers are measured, as in guinea pig serum, instead of the C'2 titers yielded by the usual titration. 2. The measurement of complement combining component or components in weight units, instead of relative terms, is carried out as in guinea pig serum and leads to similar values, 0.03 to 0.05 mg. of C' N per ml. of human serum. 3. Other similarities in human and guinea pig complements are noted and discussed.

SPECIFIC PRECIPITATION AND MOUSE PROTECTION IN TYPE I ANTIPNEUMOCOCCUS SERA

1. A rapid and simple method is given for the approximate determination of the specifically precipitable protein in Type I antipneumococcus sera. 2. It is shown that a close parallel exists between the specifically precipitable protein and the number of mouse protection units in a wide variety of Type I antipneumococcus sera. 3. Owing to the consistent results obtained and the rapidity, simplicity, and economy of the method, its use is proposed instead of the mouse protection test as a basis for the titration of standard sera and the comparison of others with a standard. 4. A method is given for conveniently preparing highly purified specific polysaccharide of Type I pneumococcus.

A QUANTITATIVE THEORY OF THE PRECIPITIN REACTION : III. THE REACTION BETWEEN CRYSTALLINE EGG ALBUMIN AND ITS HOMOLOGOUS ANTIBODY

1. A quantitative theory of the precipitin reaction based on the laws of classical chemistry has now been found applicable to the crystalline egg albumin-antibody system. Equations derived from the theory permit the calculation of the behavior of an anti-egg albumin serum over most of the reaction range after a few quantitative analyses have been made for the nitrogen precipitated. Data of other workers also conform to the proposed equations. 2. The empirical relation, shown to have advantages in the dye antidye system, may also be used for the Ea-A reaction. 3. Serum from the same animal after successive courses exhibits progressive changes which have been described graphically and quantitatively. These changes are believed to consist in the formation of more and more antibody capable of reacting with a larger number of chemically different groupings in the antigen molecule. 4. Evidence is presented that anti-egg albumin is not homogeneous, and that even after prolonged immunization the antiserum contains much low-grade antibody, incapable of forming precipitates unless more reactive precipitin is present. 5. Factors affecting the equivalence point ratio are discussed.

CHEMICAL STUDIES ON BACTERIAL AGGLUTINATION : IV. QUANTITATIVE DATA ON PNEUMOCOCCUS R (DAWSON S)- ANTI-R (S) SYSTEMS

1. The quantitative, absolute method of agglutinin estimation is extended to the reaction between Types I and II pneumococcus R (S) suspensions prepared in various ways and antisera from rabbits injected with these cells. 2. Quantitative estimations of the amount of antibody to pneumococcus C substance are also given. 3. The significance of the data is discussed.

THE SOLUBLE SPECIFIC SUBSTANCE OF A STRAIN OF FRIEDLANDER'S BACILLUS : PAPER I

1. A method is given for the isolation of a specifically reacting nitrogen-free polysaccharide from the so called E strain of Friedländer's bacillus. 2. The properties of this polysaccharide are described.

QUANTITATIVE EXPERIMENTS WITH ANTIBODIES TO SPECIFIC PRECIPITATES. II

1. Antisera have been produced in chickens with specific precipitates from Type II pneumococcus horse and rabbit antisera. 2. Specific precipitates from anti-Types I and II pneumococcus horse sera removed the same amount of antibody from the chicken anti-horse specific precipitate serum. Specific precipitates from horse antisera to diphtheria toxin and to crystalline egg albumin removed about one-half of the antibody. 3. Specific precipitates from anti-egg albumin, antipneumococcus C substance, and anti-Type II pneumococcus rabbit sera removed the same amount of antibody from the chicken anti-rabbit specific precipitate serum. 4. No antibody was removed from the chicken anti-horse specific precipitate serum by rabbit specific precipitates or from the chicken anti-rabbit specific precipitate serum by horse specific precipitates. 5. It is concluded that the antigenic specificities of antibodies from the horse and rabbit are not influenced by their particular antibody functions.

QUANTITATIVE STUDIES ON ANTIBODY PURIFICATION : I. THE DISSOCIATION OF PRECIPITATES FORMED BY PNEUMOCOCCUS SPECIFIC POLYSACCHARIDES AND HOMOLOGOUS ANTIBODIES

1. Quantitative data are given on the effect of changes in hydrogen ion concentration and of salt solutions of high concentration on certain immune precipitates obtained at lower salt concentration. 2. Advantage is taken of the shift in reaction equilibrium brought about by the salt in the case of pneumococcus carbohydrate-anti-carbohydrate precipitates to enable the preparation, in a single step from unconcentrated serum, of antibody solutions in which up to 93 per cent of the total nitrogen is immune nitrogen. The method permits successive absorptions of a serum to be made with the same specific precipitate. 3. A modification of Felton's alkaline earth hydroxide dissociation procedure is proposed which yields highly purified antibody with precipitates which have been subjected to several successive salt dissociations.

IMMUNOLOGICAL RELATIONSHIPS OF CELL CONSTITUENTS OF PNEUMOCOCCUS

1. The protein precipitated by acetic acid from solutions of pneumococci shows chemical reactions characteristic of nucleoprotein and mucoid. 2. The protein of pneumococcus, as contrasted with the non-protein soluble specific substance, exhibits species specificity rather than the type specificity characteristic of the latter.

ANTIPROTEINS IN HORSE SERA : II. ANTIBODIES TO PNEUMOCOCCUS NUCLEOPROTEIN AND THEIR REACTION WITH ANTIGEN

The antiprotein in an antipneumococcus horse serum resulting from intravenous injections of infected pleural exudate showed a precipitin type of reaction with pneumococcus nucleoprotein rather than the antitoxin type of response.

THE SOLUBLE SPECIFIC SUBSTANCE OF PNEUMOCOCCUS

1. A method is given for the concentration and purification of the soluble specific substance of the pneumococcus. 2. The material obtained by this method is shown to consist mainly of a carbohydrate which appears to be a polysaccharide built up of glucose molecules. 3. Whether the soluble specific substance is actually the polysaccharide, or occurs merely associated with it, is still undecided, although the evidence points in the direction of the former possibility.

QUANTITATIVE STUDIES ON ANTIBODY PURIFICATION : II. THE DISSOCIATION OF ANTIBODY FROM PNEUMOCOCCUS SPECIFIC PRECIPITATES AND SPECIFICALLY AGGLUTINATED PNEUMOCOCCI

1. The salt dissociation and barium hydroxide-barium chloride methods are extended to the preparation of highly purified antibody solutions from specific precipitates derived from Type III and Type VIII antipneumococcus horse sera and a low grade polyvalent bovine serum. Analytically pure precipitin (agglutinin) was obtained from the last, and Types I, II, and III antibodies were separated. 2. Difficulties connected with the application of the methods to Type I antipneumococcus rabbit sera are described, as is also the purification of antibody from low grade pig and sheep sera. 3. The dissociation of antibody by both methods from Type I pneumococci agglutinated in antisera produced in the horse, rabbit, pig, and sheep, is described and its advantages discussed. 4. Certain theoretical aspects of the work are also discussed.

A QUANTITATIVE THEORY OF THE PRECIPITIN REACTION : V. THE REACTION BETWEEN CRYSTALLINE HORSE SERUM ALBUMIN AND ANTIBODY FORMED IN THE RABBIT

1. The reaction between crystalline horse serum albumin and homologous antibody in rabbit sera is quantitatively accounted for by expressions similar to those derived from the law of mass action for other immune precipitating systems. 2. The reaction of an azo dye prepared from crystalline serum albumin by coupling with diazotized R-salt-azo benzidine was also studied with homologous antibody and anti-serum albumin. 3. Quantitative data obtained on cross reactions with the two antigens differ markedly from data on the corresponding reactions in the egg albumin system and indicate that tyrosine and perhaps histidine, while important in determining the serological specificity of egg albumin, have little connection with the specificity of serum albumin. 4. Calculations are made of the equivalent composition of the specific precipitate at various reference points in the reaction range.