THE EGG OF THE DOMESTIC CAT 163 



In the second polar spindle the chromosomes are frequently 

 adherent, or one might almost say confluent, so close is the rela- 

 tionship established. In such cases one finds a varicose thread 

 plainly consisting of several elements and a number of detached 

 bodies of chromatin which may consist of one dyad or of 

 two more or less closely united. Under such conditions man- 

 ifestly the number of distinct masses of chromatin is not the 

 number of chromosomes except in the restricted sense im- 

 plied by the derivation of the word. The greatest number 

 of units which one can certainly decipher from the confused 

 mass is the least which can be considered as the true number of 

 chromatic elements in the spindle, provided always that eggs 

 do not differ in respect to the presence or absence of accessory 

 chromosomes. 



Twelve dyads is a number frequently observed, but from the 

 study of the first spindle it is plain that there are two very small 

 ones and these two have not been seen in the second spindle, 

 apparently being obscured by being associated with other larger 

 ones. Except in one spindle the maximum number observed 

 did not exceed fourteen. In the exceptional case there seemed 

 to be sixteen. The reduced number of chromosomes is therefore 

 probably not less than fourteen. 



Fertilization 



The unfertilized tube egg is surrounded by a corona in which 

 the radiate structure is accentuated. The zona is thick. The 

 outlines of the coronal cells gradually grow indistinct, while the 

 nuclei still retain their staining power (figs. 11-12). The egg is 

 spherical, and the deutoplasm is in the condition described for 

 the ovarian egg. 



The second polar body is formed after the sperm head enters 

 the egg. 



With early fertilization stages, sperm heads are found among 

 the coronal cells in small numbers, a fact which is very reasonable, 

 since naturally one of the first to arrive will fertilize the egg. 

 With later stages they may be present in abundance. More 



