IGO AEROBIC FERMENTATIONS 



variations were found in the carbon dioxide output 

 (Parker, 1922). No conclusion as to whether this is 

 only a special case of partial transition to anaerobic 

 processes caused by a local insufficiency of oxygen or if 

 it happens even when sufficient oxygen is available can 

 be arrived at on the basis of the data at hand. This 

 would, however, be an interesting topic for further re- 

 search. 



In free-living ivorms, the only case in which, under 

 clearly aerobic conditions, organic acids were excreted 

 is that of Hirudo ( Laf argue and Fayemendy, 1932 ; Bra- 

 connier-Fayemendy, 1933). 



But aerobic fermentations are very characteristic of 

 the metabolism of parasitic helminths in oxygenated me- 

 dia. As a matter of fact the metabolism of every para- 

 sitic worm investigated so far in the presence of air either 

 definitely showed incomplete oxidations or at least gave 

 clear indications of them. The tendency is especially well 

 developed in those helminths whish lead a predomi- 

 nantly anaerobic life in nature. In Ascaris and Paras- 

 caris the formation of organic acids has been demon- 

 strated during experimental exposures to aerobic con- 

 ditions by Weinland (1901), Fischer (1924), von Brand 

 (1934a), Kriiger (1935, 1936), Oesterlin (1937) and 

 Toryu (1936) ; in Fasciola and Dicrocoeliuni by Wein- 

 land and von Brand (1926) and Flury and Leeb (1926) ; 

 in Moniezia and Diphyllohothrium by Alt and Tischer 

 (1931) and Friedheim and Baer (1933). Whether sim- 

 ilar processes occur in the acanthocephala is not yet def- 

 initely known; their presence has been suspected in the 

 case of Macracanthorhynchus, since this worm consumes 

 nearly the same amount of glycogen under aerobic and 

 under anaerobic conditions (von Brand, 1940). That 

 the afore-mentioned parasitic nematodes, trematodes and 

 cestodes actually consume oxygen is a well-established 

 fact; in addition to the data published in some of the 



