LITERATURE. 5 



two polar cells, and that not only this one-fifth, but all of the eggs, 

 produce two spindles. However, he still thinks that in 4 out of every 5 

 eggs the first spindle does not divide, but is metamorphosed directly 

 into the monaster of the second spindle, and that half of its chromosomes 

 must degenerate in the egg. Thus, in his opinion, the first polar cell in 

 four-fifths of the eggs is suppressed by the failure of the first spindle to 

 divide. He thinks that this conclusion is supported by the fact that 

 the metakinesis of the first spindle is only rarely seen. When the first 

 polar cell is formed it is cut off while the egg is in the ovary, and the 

 second spindle, too, arises before ovulation. He adds somewhat to his 

 previous description of the chromosomes, the spindles and their divisions. 

 His view has changed also in regard to the number of chromosomes in 

 both spindles. He now counts sixteen instead of twelve. Sobotta reviews 

 and criticizes the work of Gerlach, and touches on the papers of Kirk- 

 ham and Lams et Doorme. 



Sobotta (1908), in his latest paper, gives a clear summary of the 

 present state of investigation on the maturation processes, and points 

 out that he believes the mouse to be an exception to the general rule. 

 He then briefly outlines his own results and reviews and criticizes the 

 recent papers of Gerlach, Melissinos, Kirkham, and Lams et Doorme. 



