EFFECTS OF CARBON DIOXIDE ON EGGS 377 



other cells not receiving these layers retain the elongated form 

 of the chromosomes. A considerable body of evidence has been 

 produced by Boveri to substantiate this view. 



From time to time, various authors have noted exceptions to 

 the rule that the germinal cells never undergo diminution. Most 

 recently we have the work of Kautsch who has given drawings 

 of a number of cases and points out that in all of the eggs observed 

 by him, the axes of the spindles in the Po and EMSt cells were 

 parallel. This the author took as indicating that the proto- 

 plasm of the two cells was similarly structured. How the con- 

 dition arose, he does not state. A glance at either figure O or P 

 will show exceptions to this rule. In fact, in the number of eggs 

 in which I have observed this anomaly, I have been unable 

 to find any two spindles which were parallel. 



Viewed in the light of Boveri's hypothesis, the two eggs shown 

 in figures 16 and 17, prove very interesting. Here we have the 

 P2 and EMSt blastomeres fused together after division, and, if 

 the diminution process depends on a qualitative division of the 

 chromosomes, we should find some somatic and germinal chro- 

 mosomes in the spindles. But as will be seen from figure 17, 

 this is not the case. On the other hand, if the presence of the 

 elongated chromosomes depends on some specific substance car- 

 ried in the cytoplasm of the primordial germ cell, then we should 

 expect to find eight complete chromosomes in the spindles. 



A glance at figure 17, shows that the chromosomes are under- 

 going typical diminution. How is this to be explained by the 

 hypothesis advanced by Boveri? Can it be that the germ path 

 determiner (or however we choose to think of this postulated 

 substance) has lost its potency over the protoplasm which it 

 had controlled in the preceding division? Or, is the explanation 

 for the diminution process to be sought in some other theory? 

 The answer to this question is, I think, given by the protoplas- 

 mic ball which almost invariably is found in eggs showing diminu- 

 tion in the germinal cells. 



If we conceive of the presence of the elongated chromosomes 

 in the germinal cells as being due to some finely balanced quali- 

 tative or quantitative chemical inter-reactions, then it is easy 



