OXYGEN SUPPLY OF CERTAIN ANIMALS 297 



This conclusion agrees with Matthew's ('05) theory of respiration. 

 Matthew's hypothesis is that protoplasm by virtue of some 

 unknown substance is such a powerful reducing agent that it 

 is able to split up protoplasmic water into hydrogen and oxygen ; 

 the atomic oxygen going to oxidize substances, and the hydrogen, 

 either combining with atmospheric oxygen, as in aerobic respira- 

 tion or in anaerobic respiration, being set free as nascent hydrogen 

 and combined with other substances. Atmospheric oxygen, 

 according to this theory, acts merely as a depolarizer for the 

 nascent hydrogen and the only difference between aerobic and 

 anaerobic respiration is the manner in which the hydrogen is 

 taken care of. 



Packard ('07) believes that the carbohydrates injected into 

 the fish take the place of atmospheric (molecular) oxygen, as the 

 depolarizing agent for the removal of hydrogen. 



Snyder ('12), arguing from this standpoint, attempts to prove 

 that the anaerobic respiration was the primitive, fundamental 

 type, and that the 'oxygen habit' was taken on during evolu- 

 tionary development. Putter ('05) also believes that anoxybiotic 

 rnetabolism was the primitive type. 



Juday ('08) found that many Protozoa, including members 

 of the genera Pelomyxa, Difflugia, Colpidium, Gyrocorys, 

 Peranema, Coleps, Paramecium, Prorodon, Lacrymaria, Uronema 

 and Monas, lived normally for as long as four months in the lower 

 waters of Lake Mendota in the absence of free oxygen. Living 

 under these same conditions were other invertebrates, including 

 the annelid worms Tubiex and Limnodrilus; a gastrotrich, 

 Chaetonotus; an ostracod of the genus Candona; a small mollusc, 

 Pisidium idahoense; the larvae of several chironomids, and 

 occasionally the larvae of the black-winged orl fly, Sialis infumata. 

 Juday kept several of these forms in the laboratory under oxygen- 

 free conditions and found them to be practically unaffected by 

 the absence of oxygen. 



]\Iaill and Hammond ('00) recognized the resistance of chiro- 

 nomid larvae to lack of oxygen. They put six larvae in bottles 

 containing boiled water, superimposing a layer of carbonic 

 acid, and sealing with a rubber stopper. Four of the six larvae 



