NUCLEOLAR STRUCTURES OF THE CELL. 171 



of the nucleus, and then form an inextricable coil at the centre 

 of the nucleus, this being the stage of synapsis. 



In Enchistus there is a well-marked stage following the 

 synapsis, which may be termed the post-synapsis ; it is charac- 

 terized by the loosening up of the long chromosomal loops, so 

 that the latter may now be counted, which was impossible dur- 

 ing the synopsis. A careful count of the loop in a number of 

 nuclei shows that a reduction of the number of chromosomes 

 had taken place in the synapsis ; in the post-synapsis the chro- 

 matin loops (chromosomes) are of unequal length, and in differ- 

 ent nuclei vary in number from three to six, while four is the 

 usual number. It is specially to be noted here that in the post- 

 synapsis there are never exactly seven chromosomes, which 

 would be exactly half the normal number, but less than seven, 

 which fact must be brought into connection with the fact that 

 one of the earlier chromosomes had been metamorphosed into 

 the chromatin nucleolus. Interesting as the relations are from 

 the standpoint of chromatin reduction, they are not exactly in 

 line with the subject in hand, and so cannot be further described 

 here. 



After the post-synapsis follows the telophase, and then the 

 rest stage of the spermatocyte. In the latter period the chro- 

 matin nucleolus, still red in color, lies against the nuclear mem- 

 brane and encloses a large globule of lighter staining substance. 

 The true nucleolus, larger than the former, is usually unstained 

 (only browned by the action of Hermann's fixative) and lies 

 near the centre of the nucleus. The chromatin reticulum is 

 deep violet, and special chromosomes are not distinguishable. 



In the prophase of the first reduction division no continuous 

 spirem is formed, but at the stage of the dense spirem the chro- 

 matin reticulum segregates into from three to six long loops. 

 The latter are of unequal lengths, and, according to the num- 

 ber of segments present in the dense spirem stage, one or more 

 of these loops divide transversely, until in the loose spirem 

 stage always exactly seven chromosomes (exactly half the nor- 

 mal number) are evolved. This remarkable power of self-reg- 

 ulation of the number of the chromosomes has been discussed 

 more fully in another publication. In the loose spirem stage 



