INTRACELLULAR OXIDATION-REDUCTION STUDIES : I. REDUCTION POTENTIALS OF AMOEBA DUBIA BY MICRO INJECTION OF INDICATORS

37. Studies in Cheddar Cheese: I. The Oxidation-Reduction Potentials of Ripening Cheddar Cheese

1. A method is described for following the intensity of reduction (or oxidation-reduction potential) at different levels in the interior of ripening Cheddar cheese.

2. Variations in this potential throughout the course of ripening are described and mean values assessed.

3. Cheese are shown to be not homogeneous throughout their mass; outer zones of more highly oxidised condition exist near the surface of the cheese and round cracks and borings. The depth of these zones increases with the age of the cheese.

4. The values obtained can be correlated with the known bacteriological data for Cheddar cheese.

5. The significance of the data obtained in relation to cheese faults is discussed.

On the physiology of amœboid movement.―V. Anaerobic movement

The processes involved in muscular contraction stand in peculiar relation to oxidation. They occur in two stages. The act of contraction is associated with anaerobic reactions; while oxygen is only required for a recovery process (Fletcher and Hopkins, 1917). There is evidence that such a mechanism is general, not only for divers kinds of muscle (Ritchie, 1928), but perhaps also in cilia (Gray, 1928). Hill (1926) has suggested that certain common principles underlie all forms of animal movement, and many aspects of movement in amœba support this (Pantin, 1926, a and b ). An investigation of the relation of amœboid movement to the presence of oxygen is therefore necessary. The amœbæ used in the following experiments are small (100 μ X 25 μ) and cannot be obtained in large numbers free from associated organisms. It was not possible to measure their oxygen consumption or to subject them to chemical analysis. The problem had to be attacked indirectly.