TRANSITION TO ANAER0BI0SI8 155 



to a minimum when the animal is kept in water of very- 

 low salinity. His supposition that during this time non- 

 oxidized substances accumulate in the body, i.e., that the 

 metabolism has become partially anaerobic, seems well 

 founded since there was a marked increase in oxygen 

 consumption (as compared to the normal rate) for two 

 days, when the animals were again transferred to sea 

 water of normal salinity. 



In general, it is a well-established fact that many ani- 

 mals show considerable variations in the intensity of 

 oxygen intake depending upon the salt concentration of 

 the medium, but there seems to be no regularity in either 

 the direction or the extent of the change. Data concern- 

 ing Planaria, Nereis and Carcinus, to give only a few 

 examples, will be found in the papers of Schlieper (1929) 

 and Buchanan (1931). Whether, in any of these cases, 

 fermentations take place is unknown, but it is a problem 

 which deserves attention. 



