372 THEOPHILUS S. PAINTER 



sequently, some of the smears are advanced farther than others ; 

 a larger proportion of eggs reach the equatorial plate phase in 

 one slide than in another, and we find as a result a larger pro- 

 portion of tetrasters. It seems probable that in the smear with 

 over 50 per cent of the eggs showing tetrasters in the Si cell, the 

 Si blastomere had been able to bring its division only to the 

 equatorial plate phase. However, on all these points more experi- 

 mental evidence is needed and the author hopes to fill in the gaps 

 as soon as suitable material is available. 



It is of further interest to ask how the eggs were able to live 

 and develop to a slight degree, in an atmosphere of CO2. Es- 

 pecially, when they had been kept at a temperature where they 

 would normally have developed in some three weeks. These 

 questions are taken up in the following discussion. 



It has long been recognized that intestinal parasites live under 

 anaerobic conditions, but Weinland ('01) was the first to show 

 the mechanism by which they obtained the oxygen necessary 

 for their existence. It had been known previously that Ascaris 

 contained a large amount of glycogen, and Weinland was able to 

 show that when these animals were kept in a medium without 

 food, this glycogen disappeared and he obtained CO2 and valeric 

 acid. He suggested that the gylcogen had been broken down by 

 some animal ferment. Glycogen is one of the complex sugars 

 with the empirical formula of (CeHioOs)''. According to Wein- 

 land's ideas, this is broken down in essentially the following 

 way : 



(CeHieOs)^ = X (C5H10O2 — valeric acid — CO2 and 0) 



A number of authors (Brault and Loepers '04; Buschs '05, 

 '06; Kemnitz '11; and Brammertz '13) have shown that the 

 eggs of Ascaris contain large amounts of glycogen. Bram- 

 mertz was able to show that during the formation of the polar 

 bodies, the amount of glycogen diminished in the region where 

 these bodies were being formed. The reason for this was that 

 the glycogen was broken down to furnish the oxygen necessary 

 for this process. For further development the oxj^gen of the 

 air seems to be essential, although the glycogen in the egg is 



