IO4 EISE.V. [VOL. I. 



parts : chromioles, chromomeres, chromosomes, chromoplasts, 

 linoplasts, linin, chromoplasm, endochromatic granules, and 

 parachromatic granules. 



Chromioles. -- These are the most minute of the visible 

 organized and individualized primary structures of the nu- 

 cleus, and are the most important constituents of the chromo- 

 somes, probably being the carriers of heredity. They appear 

 as minute globules, staining darker than the other parts of the 

 nucleus except the chromoplasts. The chromioles are of a 

 certain size and number in every species of nucleus and in 

 every perfect chromosome. They are, as a rule, arranged in a 

 regular manner in the chromosomes and in the chromomeres. 

 During the absolute resting stage of the cell the chromioles 

 are situated free in the nucleus, connected only by tiny fila- 

 ments of linin and chromoplasm ; while during the mitotic 

 stages they are grouped into chromomeres, and these again 

 into chromosomes. With absolute resting stage is indicated 

 only absolute rest from " mitotic work." During this stage 

 active metabolism is carried on. 



There are thirty-six chromioles in every perfect chromosome, 

 and these are divided among six chromomeres, each chromo- 

 mere containing six chromioles. The chromioles are sur- 

 rounded by a connective, apparently homogenous substance 

 -the chromoplasm. The chromoplasm thus constitutes the 

 greatest bulk of the chromosome. 



The chromomeres are small aggregations of chromioles from 

 three to six in number, according to the stage of development of 

 the nucleus. The chromosomes in the polymorphous nuclei are 

 twenty-four in number, but in the other testes cells there are only 

 twelve. Each perfect chromosome contains six chromomeres. 



In the resting stage of the polymorphous spermatogonia we 

 find in the nucleus one or more large dark-staining bodies --the 

 chromoplasts (net-knots). These chromoplasts are particular 

 and most important organs of the nucleus. Their function is 

 to attract the chromioles and to arrange them first into leaders, 

 and later, through certain changes of the leaders, into chromo- 

 somes. The chromoplasts finally divide up into as many parts 

 as there are chromosomes, one part adhering to each chromo- 



