152 THE BREEDING OF ANIMALS 



The mutation appearing in the father was not only a 

 radical variation, but there existed a strong tendency to 

 transmit the abnormality. The strength with which 

 mutations are transmitted is still further indicated by 

 the later history of the sons and daughters of the father. 

 " Salvator had four children they were two boys, a 

 girl, and another boy the first two boys and the girl 

 were six-fingered and six-toed like their grandfather; 

 the fourth boy had only five fingers and toes. 



" George had only four children ; there were two girls 

 with six fingers and six toes ; there was one girl with six 

 fingers and five toes on the right side, and five fingers and 

 five toes on the left side, so that she was half-and-half. 

 The third, Andre, you will recollect, was perfectly well 

 formed, and he had many children whose hands and feet 

 were all regularly developed. 



" Marie, the last, who of course married a man who 

 had only five fingers, had four children : the first, a boy, 

 was born with six toes, but the other three were normal." 1 



Some marked variations among the domestic animals 

 which have been recorded from time to time and which 

 are probably true mutations may be mentioned. The 

 normal foot of domestic swine is cleft, but solid-hoofed 

 hogs are common, and this mutation is strongly trans- 

 mitted. The breed of swine known as " mule-footed 

 hogs " is an example. Horned sheep normally possess- 

 ing two horns are sometimes born with four horns. The 

 offspring of horned cattle are sometimes born without 

 horns, and this variation is strongly transmitted. 



To Hugo De Vries of Amsterdam we owe our present 

 definite notions regarding the theory of mutations. While 

 such variations were recognized by Darwin and other 



1 Huxley, quoted in Miles' "Stock Breeding," p. 79. 



