CHEMICAL RELATIONS OF NUCLEUS AND CYTOPLASM 339 



1 /z in diameter. At the lieight of their development they are ahnost 

 eight times their original length and twenty times their original 

 diameter. In the final period they are but 2 /x 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 Pnstiurus, at different periods, 

 drawn to the same scale. [RiJCKERT.] 



A. At the period of maximal size and minimal staining-capacity {tgg 3 mm. in diameter) 

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

 maximal staining-power. 



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

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

 substance behind. As Riickert points out, the great mcrease ot 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 ot the chromo- 

 somes and that of the ^gg points to an intimate connection between 

 the nuclear activity and the formative energy of the cytoplasm. 



