28o GENETICS 



care of the young, with the Brahma, which at intervals 

 ceases to lay eggs, broods them and takes care of the 

 young. The hybrid between the two lays eggs for a time, 

 broods them, and takes care of the young for a day or two. 



Figure 58. Hybrid between a Great St. Bernard dog and a Dach- 

 shund. After Lang (1914). 



Then it abandons the young, which die from lack of care; 

 the parent going back to the laying of eggs. 



In such cases of the formation of diverse combinations 

 of structures and functions through crossing, we approach 

 the normal operation of biparental reproduction, described 

 in Chapter XII. It is only in case the parents are very 

 diverse in their genetic systems, or in their other structures 

 and functions, that the results of crossing are prevailingly 

 harmful. If the parents are not too diverse, new combina- 

 tions are formed, some of which may be advantageous, 

 others disadvantageous, as set forth in Chapter XII. This 

 appears to be the situation in crosses of the different races 

 of man. These are not so diverse that crossing produces in- 

 juries or abnormalities. There is no evidence of incompati- 

 bility of chromosomes in the different races. And there is no 

 incompatibility of gross structures and functions such as to 

 cause the hybrids to die young. The hybrids and their descend- 

 ants show many different combinations of the characteristics 

 of the parent races. Some of these may be advantageous, as 



