CHEMICAL RELATIONS OF NUCLEUS AND CYTOPLASM 



339 



\ P in diameter. At the height of their development they are almost 

 eight times their original length and twenty times their original 

 diameter. In the final period they are but 2 p in length and i /* in di- 

 ameter. These measurements show a change of volume so enormous, 

 even after making due allowance for the loose structure of the large 

 chromosomes, that it cannot be accounted for by mere swelling or 

 shrinkage. The chromosomes evidently absorb a large amount of 



Fig. 157. Chromosomes of the germinal vesicle in the shark Pristiurus, at different periods, 

 drawn to the same scale. [RiJCKERT.] 



A. At the period of maximal size and minimal staining-capacity (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. 



matter, combine with it to form a substance of diminished staining- 

 capacity, and finally give off matter, leaving an intensely staining 

 substance behind. As Riickert points out, the great increase of sur- 

 face in the chromosomes is adapted to facilitate an exchange of mate- 

 rial between the chromatin and the surrounding substance ; and he 

 concludes that the coincidence between the growth of the chromo- 

 somes and that of the egg points to an intimate connection between 

 the nuclear activity and the formative energy of the cytoplasm. 



