262 RECENT CYTOLOGY 



differs from all other mitoses in the fact that in it an 

 actual separation of whole chromosomes takes place ; 

 it is a qualitative and not only a quantitative division. 

 It is to this mitosis that the term reducing division is 

 properly applied. 



We have to notice that at one stage of the process 

 now described the chromosomes derived from the two 

 parents are in a close state of fusion. It would seem 

 as if the actual conjugation of chromosomes, which 

 failed to take place when the conjugating gametes and 

 their nuclei fused together in the formation of the 

 zygote, was only delayed, and now occurs hundreds or 



FIG. 43- 



thousands of cell generations after the actual process 

 of fertilization, and immediately before the production 

 of those cells which are to give rise to the new 

 individual. 



It may be pointed out that, although the chromo- 

 somes which emerge from this fusion seem to be 

 identical with those which entered into it, yet it is 

 difficult to believe that they have not undergone some 

 change, or exercised some mutual influence upon one 

 another. If no such influence has been exerted, it is 

 difficult to imagine any possible reason for the process 

 of fusion taking place at all. 



In the higher plants a similar reducing division 



