EFFECTS OF CARBON DIOXIDE ON EGGS 379 



In advancing this explanation, it is not my intention to imply- 

 that diminution in the germinal cells takes place only after 

 the formation of the protoplasmic balls. In fact, I have my- 

 self found cases in which diminution was plainly taking place, 

 but I was unable to find any ball. Such eggs, however, were 

 invariably abnormally retarded in their development and the 

 explanation for the diminution is probably to be found in another 

 cause. The author ('15) has shown that in the sea urchin egg, 

 after fertilization, progressive changes are going on in the 

 cytoplasm of the egg w^hich are independent of the cleavage 

 process and thus we may have the formation of the micromere, 

 which normally comes in the 16-cell stage, in the 8- or 4-cell 

 stage. It is very probable that this process is characteristic 

 of all eggs. Thus in the germinal cells of Ascaris we may imagine 

 series of changes are going on, only here they tend toward dif- 

 ferent results. Were the germinal cell long delayed in its divi- 

 sion it may be that the somatic tendency becomes so strong as 

 to suppress the germinal one, and thus diminution takes place. 



BIBLIOGRAPHY 



Boring, A. M. 1909 A small chromosome in Ascaris meg. Arch. f. Zellforsch., 



Bd. 4. 

 Boveri, Th. 1899 Die Entwicklung von Ascaris meg. mit besonderer Riick- 



sicht auf die Kernverhaltnisse. Festschr. f. Kupffer. 



1909 Uber 'Geschlechtschromosomen' bei Nematoden. Arch. f. Zell- 

 forsch., Bd. 4. 



1910 a Uber die Teilung zentrifugierter Eier von Ascaris megalo- 

 cephala. Festschr. f. W. Roux., Arch. f. Entw.-Mech., Bd. 3. 



1910 b Die Potenzen der Ascaris-Blastomeren bei abgeanderter 



Furchung. Festschr. zum 60. Geburtstag R. Hertwig, Bd. 3. 

 Brammertz, W. 1913 Morphologic des Glycogens wahrend Eibildung und 



Embryonalentwicklung von Wirbellosen. Arch. f. Zellforsch., Bd. 11. 

 Brault et Loepers 1904 Le glykogene dans le developpement de certains 



parasites. Journ. de Physiol, et Pathol. Gcnerale, tom. 6. 

 Busch, p. W. C. M. 1905-1906 Sur la localisation du glykogene chez quel- 



ques parasites intestinaux. Arch. Intern, de Physiologie, tom. 3. 

 Edwards, C. L. 1910 The idiochromosomes of Ascaris megalocephalaand 



Ascaris lumbricoides. Arch. f. Zellforsch, Bd. 5. 

 Kautschz, G. 1912 Studien uber Entwicklungsanomalien bei Ascaris. Arch. 



f. Entw.-Meck., Bd. 35. 



