28 EISEN. [Vol. XVII. 



In the polymorphous cells the chromosomes divide through 

 common or somatic mitosis ; in the following stages the auxo- 

 cyte divides through heterotypic mitosis, while in the sper- 

 matocytes the mitosis is the homoeotypic one. 



In the end of the anaphase of the two maturation cells the 

 chromosomes enter an almost perfectly confluent stage, in 

 which the individual chromosomes have lost their individuality, 

 being fused into a single umbrella-like mass. From this mass 

 the individual chromosomes reappear, but it seems almost 

 incredible that the new chromosomes should be composed, 

 each one of them respectively, of the same identical chromo- 

 meres and chromioles as before mitosis. 



The changes which the chromosomes undergo in the matura- 

 tion cells will be more particularly described under the chapter 

 on mitosis. The chromosomes of the spermatocytes possess 

 the peculiarity to take the congo stain after the haematoxylin, 

 which causes them to appear reddish-black instead of pure 

 black, as do the chromosomes of the auxocytes. 



The chromosomes of the auxocytes are bretzel-shaped, while 

 those of the spermatocytes are J^^-shaped before mitosis. The 

 bretzel form is due to the fact that the ends of the chromo- 

 somes overlap each other instead of growing together. 



The chromosomes in all these varieties of cells divide by 

 equation division, and not by reduction division. 



The CJirovwplast and the Endocliromatic Granules. — This 

 body, which I consider to be of the greatest importance in the 

 evolution of the nucleus, has been variously known as nucle- 

 olus, netknot, karyosome, etc., but as these names have also 

 been applied to other structures in the nucleus, I consider my- 

 self justified in proposing for it a new and more distinct name, 

 the " chromoplast," thus indicating at least one of its char- 

 acteristic properties in connection with the chromosomes. 



In the Batrachoseps testes the chromoplasts are most dis- 

 tinctly individualized in the resting stages of the nucleus, and 

 in those stages in which the chromosomes have not yet reached 

 their final and perfect form. They may, however, still be seen 

 in the metaphase of the auxocytes, but after that stage is passed, 

 they become less distinct, or may even so fuse with the chromo- 



