The Laws of Heredity. 175 



young ones. The aphides thus produced were able themselves to 

 produce others. Bonnet placed one apart, and obtained from it 

 five successive generations without the aid of a male. An aphis 

 of the fifth generation produced young under the same conditions, 

 and Bonnet saw this fecundity prolonged through over ten genera- 

 tions. This viviparous condition ceased in the autumn, when the 

 males begin to appear ; then the aphis becomes oviparous. 



This is a curious example of the influence of the male on a 

 whole series of generations, fecundated as it appears by one single 

 act. Facts of a like nature occur in certain caterpillars, and in 

 some species of molluscae. 



Among the higher animals it is still more easy to study the 

 heredity of influence. Burdach 1 gives the following examples. 



When a mare is crossed by an ass and produces a mule, if she 

 be afterwards put to a stallion, the colt she then drops will have 

 some points of resemblance to the ass. 



An English mare which in 1815 was once covered by a quagga 

 gave birth to a mule marked with spots ; she never saw the quagga 

 again. In 1817, 1818; and 1823, she was covered successively by 

 three Arab stallions, and produced three brown colts with bands 

 like those of the quagga. 



A sow which had had by a wild boar a litter in which the brown 

 colour of the sire was predominant, was put, long after his death, 

 to boars of domestic breeds ; among the pigs of the second and 

 third litters were several having patches of the colour of the wild 

 boar. 



If a bitch be once put to a dog of another race, every litter 

 of puppies afterwards will include one belonging to that other 

 breed, except the first time she be put only to dogs of her own 

 breed. 



' It is the same with the human species/ says this physiologist. 

 ' We sometimes find the children of a second marriage resembling 

 the former husband, who may be long since dead, and showing a 

 closer relation to him, even from the moral point of view, than to 

 their true father/ 



Burdach is content with affirming this without citing any instance. 



1 Traitt de Physiologie, ii. 243. 



