90 MAN, — THE ANIMAL 



into a typical nucleus. This nucleus nas a definite 

 number of chromosomes (23 or 24 in man) which 

 now unite in a re-mating relationship with the egg 

 chromosomes. In so far as the father is con- 

 cerned then, the chromosomes are the only bodies 

 that can be responsible for transmitting parental 

 characters. 



In this connection, we naturally ask, "What is 

 the cause of maleness or femaleness, and can it 

 be determined?" There have been more than one 

 hundred theories which have had for their 

 purpose the determination of sex. None of them 

 has any standing to-day. The use of the phrase 

 "determination" of sex is unfortunate because no 

 one can in advance determine that an offspring 

 shall be male or female. One gains a much 

 clearer conception of the process if the word "ex- 

 planation" is substituted in the above expression 

 so that it reads, the explanation of sex. There is 

 a large body of scientific evidence that sex is fixed 

 when the sperm enters the ovum. In man, for 

 example, if the number of chromosomes in the 

 sperm is 23, the resulting offspring will be a male 

 child. If the number is 24, the child will be a 

 female. There is absolutely no way of predicting 

 which number the impregnating sperm will have 

 nor is there any way of influencing the result. 



Keeping in mind these great, fundamental con- 



