ANAEROBIC METABOLISM 219 



to assume that other secondary processes occur that so 

 far have not been elucidated. Weinland thought it pos- 

 sible that some oxygen dissolved in the minced mate- 

 rial might give rise to a new fatty acid molecule with 

 one carbon atom less than the one from which it orig- 

 inates. 



While true higher fatty acids do not seem, on the 

 whole, to be suitable substrates for anaerobic processes, 

 higher hydroxyacids appear to be a better source of en- 

 ergy, at least from a theoretical standpoint. Though 

 rare in invertebrates, they have been found in relatively 

 large amounts in Moniesia (Oesterlin and von Brand, 

 1934). It is not yet known whether they are actually used 

 by these tapeworms in case of oxygen deficiency. 



The second chief component of a neutral fat, glycerol, 

 has much more oxygen in its molecule than the fatty acids, 

 and the oxygen atoms are more uniformly distributed 

 amongst the carbon atoms. A shifting similar to that 

 suggested in carbohydrates is therefore possible. Barnes 

 and Grove (1916) assume that in larvae of Attagenus 

 imdulatus, kept with a very limited oxygen supply, the 

 fat is first hydrolyzed into fatty acids and glycerol and 

 that only this latter substance is used for the anaerobic 

 production of energj^ They argue that the amounts of 

 carbon dioxide found were too large to be accounted for 

 by a reduction of fatty acids, and that a derivation from 

 glycerol was more plausible. These authors further- 

 more searched for hydrocarbons, which would result 

 from fatty acids, but they found only traces of them. In 

 judging Barnes and Grove's work one should recall the 

 question raised in the preceding chapter, namely, whether 

 the oxygen was excluded sufficiently in their experi- 

 ments to prevent an aerobic oxidation of fat. 



3. PROTEINS 



Protein molecules are very large and complex and their 

 anaerobic degradation is little understood, even in micro- 



