72 BIOLOGY AND SOCIAL PROBLEMS 



The mature egg about to be fertilized rep- 

 resents all the material of maternal origin at 

 this early stage in development. This mate- 

 rial consists of the protoplasm of the egg and 

 of certain nuclear bodies called chromosomes 

 because of the ease with which they become 

 colored in artificially stained preparations. 

 These chromosomes are peculiar in that they 

 are very constant in number for the eggs, 

 sperm, or other cells of a given animal. In 

 the human being, because of the unfavorable- 

 ness of the material and of the difficulty in 

 getting it in a well-preserved condition, the 

 number of chromosomes has probably not 

 been finally determined. According to the re- 

 searches of Winiwarter, published in the last 

 few years, the number of chromosomes in the 

 ordinary cells of the human body is forty- 

 seven in the male and probably forty-eight in 

 the female. As just intimated, however, these 

 determinations may not be final, but whatever 

 the number may actually prove to be, it is 

 probably not far from what has just been 

 mentioned. It is remarkable that in practically 

 all animals the number of chromosomes in the 

 mature egg cell is half that found in the ordi- 

 nary cells of the body of the female for the 



