22 TABOO AND GENETICS 



new cells have only half the original number 

 of chromosomes. Each of these divides again 

 by mitosis (the chromosomes splitting length- 

 wise), the half or haploid number remaining. 

 The result is the gametes (literally " marrying 

 cells " — from the Greek gam^, signifying mar- 

 riage). Those from the male are called sperms 

 or spermatozoa and those from the female eggs 

 or ova. (The divisions to form ova present 

 certain complications which need not be taken 

 up in detail here.) Of the 24 chromosomes in 

 each sperm or egg we are here concerned with 

 only one, known as the sex chromosome because, 

 in addition to transmitting other characteristics, 

 it determines the sex of the new individual. 



Neither the ovum nor the spermatozoon (the 

 human race is referred to) is capable alone of 

 developing into a new individual. They must 

 join in the process known as fertilization. The 

 sperm penetrates the egg (within the body of 

 the female) and the 24 chromosomes from each 

 source, male and female, are re-grouped in a new 

 nucleus with 48 chromosomes — the full number. 



The chances are half and half that the new 

 individual thus begun will be of a given sex, 

 for the following reason : There is a structural 

 difference, supposed to be fundamentally chemi- 

 cal, between the cells of a female body and those 

 of a male. The result is that the gametes 

 (sperm and eggs) they respectively produce in 



