CHEMICAL RELATIOXS OF NUCLEUS AND CYTOPLASM 245 



bination with albumin has taken place. This is illustrated in a very 

 striking way by the history of the egg-nucleus or germinal vesicle, 

 which exhibits the nuclear changes on a large scale. It has 

 long been known that the chromatin of this nucleus undergoes 

 great changes during the growth of the ^g^, and several observers 

 have maintained its entire disappearance at one period. Ruckert 

 first carefully traced out the history of the chromatin in detail in the 





Fig. no.— Chromosomes of ihe germinal vesicle in the shiirk Pristiiiriis, at different Deriods 

 drawn to the same scale. [RiJCKERT.] 



A. At the period of maximal size and minimal staining-capacitv (egg 3 mm. in diameter) 

 B. Later period (egg 13 mm. in diameter). C. At the close of ovarian life, of minimal size and 

 maximal staining-power. 



eggs of sharks, and his general results have since been confirmed by 

 Born in the eggs of Triton. In the shark Pristiuriis Ruckert (92, i) 

 finds that the chromosomes, which persist throughout the entire 

 growth-period of the &gg, undergo the following changes (Fig. 1 10) : 

 At a very early stage they are small, and stain intensely with nuclear 

 dyes. During the growth of the ^gg they undergo a great increase 

 in size, and progressively lose their staining-capacity. At the same 

 time their surface is enormously increased by the development of 

 long threads which grow out in every direction from the central a.xis 



