OTHER RHYTHMS OF THE ORGANISATION 75 



maturation. Every animal species has in its cells 

 an equal number of chromosomes, and the male and 

 female element an equal number of these same 

 elements. 



The most curious thing in these phenomena of 

 reduction or ripening is that, as in the current 

 cellular division, the half of the chromosomes result- 

 ing from the unfolding unite within the same cell 

 in one of the poles ; in the phenomena of reduction, 

 on the other hand, as its name indicates, half of the 

 chromosomes do not unite in the poles, but are 

 expelled from the cell. The first expulsion is 

 followed by a second, so that if there are eight 

 chromosomes they are reduced to two, which is 

 when the cell is incomplete. This want of equi- 

 librium is most important, because it is the same 

 as the male and female elements undergo ; the 

 spermatic cell and the ovule cell suffer a similar loss 

 of equilibrium after their reduction. 



Reduction in the Ovum (Ascaris megalocephala). 

 In this explanation and the plan accompanying it 

 we see the double division suffered by the ovum in 

 being fertilised, a division always parallel to that 

 suffered by the zoospore of the same species. The 

 parallelism is the more exact, inasmuch as both 

 eliminate the same number of chromosomes. 



The phase 1 of fig. 17 represents the moment in 



