308 THOS. H. MONTGOMERY, 



sharply define the successive stages. The loûgitudinal split of the 

 chromosomes widens; during this process the previously undivided 

 axial linin band of the chromosome splits into two parallel bands, 

 each with its row of chromatin granules. When this split of the linin 

 axial band is accompHshed one finds joining every two genetically 

 related chromatin granules a delicate linin fibril, which bridges over 

 the split of the axial band. I could not determine how these delicate 

 fibrils are produced , but would consider it probable that they are 

 derivations of the axial band of linin rather than fibrils which have 

 arisen sui generis, and accordingly in the diagram 261 of Plate 25. 

 I have colored them in red to show this probable connection with the 

 linin spirem. 



At the beginning of the telophase the boundaries of the several 

 chromosomes can be clearly distinguished (Figs, y 1—97), but they 

 gradually become more difficult to determine (Figs. 98, 99), owing to 

 the increase in length and diameter of the chromosomes. The spaces 

 between granules placed serially behind one another in the chromo- 

 some increase in length, as well as do the spaces marking the longi- 

 tudinal split of the granules. It would seem probable that this gradual 

 displacement of the chromatin granules is effected by the contraction 

 of those delicate linin fibrils which connect granules of one chromo- 

 some with gTanules of another. The separation of the granules takes 

 place most slowly at the central ends of the chromosomes, so that 

 when nuclei are viewed from their central poles (Figs. 92, 93) the 

 outlines of the individual chromosomes can be readily distinguished. 



V. The Rest Stage of the Spermatocytes. 



The telophase passes gradually into the rest stage. 



Particular attention was given to the arrangement of the chromatin 

 in the rest stage, in order to determine whether the previously well- 

 outlined chromosomes of the telophase could be individually recognized, 

 that is, to try to learn whether the chromosomes preserve their in- 

 dividuality or independence throughout the rest stage. I started with 

 the assumption, and expected to find it fulfilled, that such individuality 

 would not be preserved, but found that the facts in Peripatus point 

 very strongly for its maintenance. 



The condition of the chromatin in the resting nucleus is as 

 follows (Figs. 100 — 109): isolated chromatin granules, chains of 

 granules, and irregular masses of granules have a relatively even 



