ANAEROBIC METABOLISM 229 



vomitoria (Weinland, 1906). As was indicated previous 

 ly, fat appears to be the mother-substance in this case. 

 One may recall that Weinland used minced material; 

 whether the same phenomenon takes place in intact spec- 

 imens is not certain. 



Traces of hydrogen have been described as liberated by 

 Ascaris (Weinland, 1901), but von Brand (1934a) could 

 not obtain confirmation of this finding. Very small 

 amounts of hydrogen have also been found in larvae of 

 Attagenus undulatus (Barnes and Grove, 1916) under 

 conditions that were not absolutely anaerobic, but in 

 which the oxygen supply was clearly deficient. 



It is well established, on the contrary, that neither the 

 earthworm (Lesser, 1910) nor the larva of Tenebrio mo- 

 litor (Gilmour, 1941) produces even traces of combus- 

 tible gases when kept under strictly anoxic conditions. 



5. ENZYMES 



That the anaerobic metabolism of invertebrates is gov- 

 erned by enzymes which exert their action even if the 

 cellular structure is destroyed has been recognized long 

 ago. Weinland (1902) was the first to show that the 

 anaerobic metabolism of Ascaris remains unchanged if, 

 instead of intact animals, minced material is used (as in 

 the case of Buchner's Prcssaft). In Parascaris, on the 

 other hand, Fischer (1924) found that only lactic acid is 

 formed and phosphoric acid liberated when the material 

 is minced (experiments ai the oxygen tension of atmos- 

 pheric air), while it is Well known that the chief end prod- 

 ucts of similarly kept intact worms are lower fatty acids. 



For information concerning the corresponding phases 

 of the anaerobic metabolism of insects, we refer the 

 reader to the papers of Barnes and Grove (1916) and 

 of Blacklock, Gordor and Fine (1930). 



In recent years more intensive studies of the enzymes 

 have been undertaken m cases of anaerobically kept in- 



