THEORY OF EVOLUTION 



95 



quarter next divides. The process continues^ 

 until a large number of cells is formed and out 

 of these organs mould themselves. 



At every division of the cell the chromosomes 

 also divide. Half of these have come from the 

 mother, half from the father. Every cell con- 



FiG. 48. Section of the egg of the beetle, Calligrapha, show- 

 ing the pigment at one end where the germ cells will later 

 develop as shown in the other two figures. (After Hegner.) 



tains, therefore, the sum total of all the chro- 

 mosomes, and if these are the bearers of the 

 hereditary quahties, every cell in the body^ 



