No. 2.] THE OVARIAN EGG OF LIMULUS. I 71 



the chromatin is the basis of the structure that underlies these 

 polar differentiations. As a matter of fact, the chromatin of the 

 germinal vesicle seems to vanish when the metabolic processes, 

 concerned with the elaboration of food, are at an end. 



The peculiar arrangement of the chromatin in the spireme 

 stage, and the various phases of karyokinesis (PI. XIV, Figs. 

 33-37) seen in the dividing oogonia do not appear to me to 

 be evidence of an organization existing in the chromatin, but 

 rather an orderly arrangement of an inert mass, brought about 

 by a structural basis which is common to the cytoplasm and 

 nucleus alike. 



The division of the oogonia is manifestly a division of the 

 structural basis of both the nucleus and the cytoplasm, and 

 the orderly separation of the chromosomes is due to an orderly 

 separation of the spindle fibers. These spindle fibers I can 

 regard as nothing else than the reticulum of the cytoplasm 

 and the reticular basis of the nuclear network combined. 

 The vital manifestations reveal themselves, not in the passive 

 chromosomes, but in the centrosome, and in the network of 

 which it is a part. The entire history of the chromatin offers 

 nothing on which to base the assumption that it is the con- 

 trolling element. 



The unia.xial feature, which is so prominent in the spindle 

 stage of the dividing oogonia (PI. XIV, Figs. 36-3S), continues 

 to exist throughout the history of the ovarian egg, and can 

 be accounted for only by the assumption of a continuity of 

 structure. It is inherent in the living matter of the egg. 

 Dr. Eycleshymer ('95) has reviewed the literature on this sub- 

 ject, and has tested the relation of the polarity in the am- 

 phibian egg to cleavage and to the orientation of the embryo. 



Peripheral bodies and yolk-nuclei. — On the same slide can 

 be seen the wide contrast between the eggs that are still in 

 the first period and those that have entered upon the second 

 period. In haematoxylin the former are dark blue, while the 

 latter are a very light blue. If the slide be dipped into picric 

 acid, previous to mounting in balsam, the former are not 

 affected, while the latter have yielded their former stain for 

 the new. The same result is obtained by means of borax-car- 



