INHERITANCE, VARIATION AND SELECTION. 35 



In a litter of pigs two young ones appeared with the marks of 

 the Berkshire that had been used as a cross twenty-eight years 

 before. 23 



A man who had a double tooth in place of one incisor inherited 

 that peculiarity from his paternal grandfather. Another man, 

 healthy in every particular, but the son of a lame man, had children 

 by three wives, and all of these children were lame like their grand- 

 father. 24 



PARTIAL TRANSMISSION. 



A very common occurrence is partial transmission, or trans- 

 mission to part of the offspring and not to all of them. Several 

 of the cases previously mentioned come under this head. Helm 

 mentions one 25 which illustrates it very well. One member of a 

 family had the second and third toes united, and this anomaly 

 was transmitted for three generations to one person only in each 

 generation out of an average of eight descendants in each family. 



Napoleon died of a cancer, a disease which he had inherited 

 from his father, but the other members of the family were not 

 afflicted with it. 



A case somewhat different but more marked is given by Qua- 

 trefages. 26 In 1803 or I ^ O 5> M. Decemet discovered in his garden 

 at Saint Denis, in the midst of a bed of acacias (Rubina psudo- 

 acacia) an individual without thorns which he describes under the 

 epithet spectabilis. It is to the multiplication of this individual by 

 the arts of the gardener that all the thornless acacias now distributed 

 in every part of the globe owe their origin. Now these individuals 



(23) Animals and Plants Under Domestication, Vol. II, p. 68. 



(24) Miles, Stock Breeding, p. 71. 



(25) American Roadsters, p. 13. 



(26) The Human Species, p. 38. 



