THE EGG OF THE DOMESTIC CAT 161 



first of the two spindles above mentioned to the effect that there 

 may be sixteen, receives some support from somewhat uncertain 

 evidence of a similar nature from a second polar spindle studied, 

 in which it seems possible that there may be sixteen dyads. Thus 

 with respect to the reduced number of chromosomes in the cat's 

 egg the most that can be said is that it is probably between four- 

 teen and seventeen. Winiwarter and Saintmont believe that the 

 somatic number of chromosomes in the cat is thirty-six and that 

 the number in the first spindle is tweWe (Arch, de Biol. T. 24, 

 p. 197). They call attention to a similar discrepancy which they 

 say occurs in the rabbit where the somatic number is forty-two 

 and the reduced number ten or twelve. 



The first polar body 



Omitting those cases in which eggs escape from the ovary 

 abnormally, as already noted, and speaking roughly with refer- 

 ence to the time element, all eggs which reach the tube organize 

 the first polar spindle and extrude the first polar body within the 

 ovary during the second day after pairing has occurred. 



This polar body (figs. 9-10 and 11) does not disappear readily 

 as the homologous structure does in the mouse (Kirkham '07; 

 Lams and Doorme '07) but its chromatin is usually demonstrable 

 even when an egg is far advanced in degeneration, or in the two- 

 cell stage. Its chromatin may exist as a number of threads or 

 granules, or may be gathered together in a single thread or in 

 a compact mass. No evidence has been obtained indicating that 

 the more compact forms ever take upon themselves the structure 

 of a true nucleus, as noted by Kirkham ('07) to occur in the second 

 polar body of the mouse, and incorrectly figured by Melissinos 

 ('07) as occurring in both polar bodies of the same species. 



In contrast to the condition commonly occurring in the mouse 

 and noted by nearly all who have worked upon it, as well as in 

 the bat (Van der Stricht '09) and the guinea pig (Rubaschkin 

 '05), no polar bodies have been observed containing a mitotic 

 figure. Very few have been found which by their equal division 

 or equal distribution of the chromatin in the two daughter cells 



