EFFECTS OF CARBON DIOXIDE ON EGGS 373 



slowly used up as development goes forward, Brammertz re- 

 gards this glycogen as a sort of reserve to tide the embryo over 

 unfavorable conditions. He cites one experiment in favor of 

 this view, which is quite similar, in its conditions, to the experi- 

 ments recorded above. He found that if eggs were placed in 70 

 per cent alcohol, part of them developed as far as the two cell 

 stage before they were penetrated by the alcohol and killed. 

 He regards it as improbable that the eggs could have gotten the 

 oxygen necessary from the alcohol, and thinks there is proof 

 here that the glycogen was used for this purpose. 



The author has not made any experiments with the eggs treated 

 wdth COo but the conditions are so similar with the experiment 

 cited that it seems very probable that the eggs used in my exper- 

 iments were able to live over this period of three months be- 

 cause of the presence of the glycogen stored in their protoplasm. 



ANOMALIES 



Under this heading I wish to record some observations made 

 on the treated eggs, which have a bearing on the problems of 

 sex determination and the cause of diminution in Ascaris megalo- 

 cephala. 



In the dividing primordial germ cells, occasionally eggs have 

 been seen in which there were, besides the four chromosomes, 

 additional elements (in 13 cases out of 123 eggs taken at random). 

 Typically there is only one additional chromosome, as in figure 

 J, but cases with two, three, four, and even eleven fragments 

 have been seen (fig. L). The way in which the single element 

 behaves during division is shown in figures K, M, and N. Cases 

 with more fragments could not be followed through division. 



The presence of one or more chromosome fragments in the 

 primordial germ cells of Ascaris megalocephala have been de- 

 scribed by a number of authors, and at the present time two 

 views have been advanced to explain them. According to Boring 

 ('09) and Boveri ('09), they represent the accessory chromo- 

 somes in this species. This is the view generally accepted. 

 Kautsch ('13), however, has shown that another interpretation 



