OXYGEN SUPPLY OF CERTAIN ANIMALS 303 



If, then, chironomid larvae are active during the period when 

 oxygen is absent, whence comes the oxygen which would liberate 

 the energy stored up in their bodies? As was stated before, their 

 activity does not consist of a few movements. They burrow 

 through the mud, making new tubes, and even when lying in 

 their tubes keep up an almost constant waving of the posterior 

 parts of their bodies. 



1. Anoxyhiotic source of energy 



It is possible that the stagnated region at the bottom of Lake 

 Mendota is an absolutely anaerobic environment, and that a 

 fermentative process, an incomplete breakdown of the organic 

 food-stuffs goes on within the body of a chironomid larva, which 

 without oxygen would result in the production of energy. Such 

 an explanation for energy production has already been cited 

 (p. 296) relating to experiments on Ascaris, pupae of flies, etc. 

 In the cases cited the energy needed is obviously small. It 

 seems rather improbable that such a process could supply suffi- 

 cient energy to meet the requirements of so active an organism 

 as the chironomid larva under consideration and keep up the 

 supply through so long a period of time. In the case of the 

 chironomid larva, however, the writer found that individuals 

 placed in oxygen-free water taken from the stagnant region of 

 Lake Mendota succumbed to 0.000032 mol. KCN on the third 

 day. Larvae exposed to weaker solutions of KCN lived longer, 

 the length of time being roughly proportional to the strength 

 of the KCN solution used. Inasmuch as KCN owes its poisonous 

 properties primarily to its interference with oxidation processes 

 and destruction of the respiratory center, the fact that the 

 larvae were killed by the small amount of the cyanide indicates 

 that an oxidation process was going on in their bodies even though 

 oxygen could not be demonstrated in the surrounding medium. 



Furthermore, if a process similar to the one that Weinland 

 ('06) postulates for the pupae of flies is furnishing energy for 

 the chironomid larva when its usual supplj^ of oxygen is cut off, 

 what explanation is to be made for the presence of haemoglobin? 

 It does not seem reasonable that so complicated a mechanism 



