ANAEROBIC METABOLISM 201 



is of the opinion that the analogy between the two cases 

 warrants the assumption of identical processes ; he there- 

 fore assumes that in Tuhifcx, as in the muscle, the source 

 for the newly-formed polysaccharide is lactic acid. He 

 must then further assume that the worm is able to ex- 

 crete part of the acid formed during the anoxic period, 

 in order to account for the reduced quantity of glyco- 

 gen resynthesized. Pending a direct lactic acid deter- 

 mination, one can just as well assume (von Brand, 1934) 

 that glycogen is reformed from other substances, e.g., 

 from fatty acids, and it might well be that such a process 

 is less effective than the resynthesis from lactic acid. 

 The whole question should be reinvestigated. 



These examples may suffice to show how the assump- 

 tion of lactic acid fermentation is often unwarranted. 



We now turn to those cases in which the occurrence of 

 glycolysis has a3tually been proven. One has to distin- 

 guish here between two possibilities. In some organisms 

 lactic acid is the only organic acid produced in anaerobic 

 carbohydrate metabolism; such organisms form an ex- 

 act parallel to vertebrates. In many other organisms, 

 however, this acid is but one of several end products and 

 sometimes it plays, from a quantitative standpoint, only 

 a minor role. These latter cases will be discussed in the 

 section dealing wdth mixed fermentations. Here we shall 

 consider only pure glycolysis as it occurs in malaria par- 

 asites, in echinoderms and in molluscs. 



Silverman, Ceithaml, Taliaferro and Evans (1944) 

 demonstrated in quantitative experiments that lactic acid 

 accounts for practically all the glucose disappearirg from 

 the medium when Plasmodium gallinaceum is kept under 

 anaerobic conditions. Previous to this work only a nega- 

 tive observation on the metabolism of malaria parasites 

 had been recorded, namely, that pyruvic acid is not pro- 

 duced by Plasmodium knowlesi in the absence of oxygen 

 (Wendel and Kimball, 1942). 



