76 HELEN DEAN KING. 



first appear they stain very faintly, but they soon take the deep 

 carmine stain characteristic of chromatin, and then fuse into sev- 

 eral large, irregular clumps. 



III. THE FORMATION OF THE FIRST POLAR SPINDLE. 



The line of radiation, shortly after the appearance of the chro- 

 matin granules, is shown in Fig. I. It is a short, fibrous band 

 with its ends, usually, though not invariably, slightly curved 

 in towards the center of the egg. This structure, which is to 

 become the first polar spindle, lies some distance below the 

 surface of the egg in a small accumulation of granular substance 

 formed, possibly, from the karyoplasm of the germinal vesicle. 

 Its longitudinal axis may be either parallel or oblique to the 

 surface of the egg, the latter position being the more common. 

 Running out in every direction from the compact meshwork of 

 fibers are numerous fine, thread-like rays which are longest and 

 most numerous at the middle of the forming spindle where they 

 extend out between the yolk spherules and seem to be continu- 

 ous with the cytoplasmic network of the egg. 



Collected near the middle of the spindle is a mass of small 

 chromatin granules which are of uniform size and stain but faintly 

 in comparison with the chromosomes of an earlier and of a later 

 period. There is a very large number of these granules and it 

 is quite impossible to count them satisfactorily ; two other sec- 

 tions of the same egg each show as many granules as are shown 

 in Fig. i. 



The nucleoli from the germinal vesicle appear at this period as 

 irregular, yellowish green, refractive bodies which are scattered 

 throughout the upper hemisphere of the egg, often lying quite 

 close to the spindle. They disappear at different times in differ- 

 ent eggs. Sometimes they have all been absorbed before the 

 chromosomes have divided ; sometimes they can still be found 

 after the first polar body has been given off. I have never found 

 any traces of them, however, after the spermatozoon has entered 

 the egg. 



Not more than fifteen minutes after the stage of Fig. I, the 

 chromatin granules begin to fuse into irregular-shaped clumps. 

 The number and size of these clumps vary greatly in different 

 eggs, in some cases there are but four or five of them, in others 



