104 THE BOTANICAL MAGAZINE. [Voi. xxxv. No. 4i4. 



f 

 is some probability, that certain mechanisms exist, possibly during 



the process of shortening, which give such a basis to the telophasic 

 chromosomes as to present a feature of zigzag or coiled arrangement 

 of the essential parts. This arrangement, by condensation, develops 

 directly into the new chromosomes, and thus the individuality of 

 chromosomes may be maintained from generation to generation of 

 the nuclear life-cycle. 



If we admit a true split in the telophase, we must assume that 

 the chromatic parts of an old chromosome, which form both sides of 

 the reticulate band, represent new chromosomes. Both sides of the 

 reticulate band will appear again in the prophase of the next nuclear 

 life-cycle in the same way as they were in the preceding telophase. 

 Thus they must develop further into definitive chromosomes in a pair- 

 ed arrangement side by side ; but our studies reveal that such is not 

 the case. New chromosomes never appear as double threads running 

 together in a straight, zigzag or spiral course, as we should expect 

 if we regard the split in the telophase as a true one. They are 

 single threads taking the form of a zigzag or irregularly coiled thread. 

 The so-called longitudinal halves of the old chromosomes separa- 

 ted by an assumed split in the telophase do not develop into two 

 definitive chromosomes but taken together i^roduce a single zigzag or 

 coiled new chromosome. They can not, therefore, be regarded as in- 

 dependent daughter chromosomes ; and they do not retain their in- 

 dividuality through the whole interkinesis from the beginning of 

 telophase' to the end of the next prophase, where the definitive 

 chromosomes can easily be seen. There is therefore no evidence to 

 support the view that a true longitudinal splitting of chromosomes 

 occurs in the telophase, and no reason to oppose the hypothesis of 

 parasynapsis by assuming the two members of the ampliitenc threads 

 to be sister chromosomes that are reuniting after a temporary 

 separation. 



The writer has the pleasant duty to offer his sincerest thanks to 

 Professor E. B. Wilson tinder whose suggestion and advice the pre- 

 sent work has been carried on, and through whose kindness all 

 facilities have been given. The writer's thanks are also due to Pro- 

 fessor R. A. Harper who has very kindly given the liberty to use 

 his laboratory during the summer vacation, and to Professor L. W. 

 Sharp in Cornell University, who has, during the writer's visit to 



