INHERITANCE OF ACQUIRED CHARACTERS 167 



of " direct action of the male element on the mother 

 form." He remarks further that " the male element 

 not only affects, in accordance with its proper function, 

 the germ, but the surrounding tissues of the mother 

 plant." 



Spencer likewise admitted the probability of the pas- 

 sage of the germ-plasm from the growing embryo into the 

 maternal tissues and thus to the germ-cells. Weismann 

 held that if any such influence in reality existed, it could 

 be explained only on the theory that some of the sperm- 

 cells of the male penetrated to the undeveloped ova and 

 there accomplished a partial impregnation. Some prac- 

 tical .breeders, of horses and dogs particularly, were so 

 thoroughly impressed with the possibility of such an 

 influence that they would not buy a highly bred animal 

 that had borne offspring to another breed, believing that 

 such a female could not be trusted to breed true. Some 

 farmers in the mule-breeding districts have reported 

 that horse foals from mares which had previously pro- 

 duced mules, sometimes possessed " mulish characters." 

 These characters which are commonly possessed by the 

 hybrid appearing thus in pure horse foals were supposed 

 to have come about through the influence of the jack on 

 the mother at some previous mating. 



158. The Lord Morton mare. One of the most 

 striking cases of supposed infection was reported to the 

 Royal Society 1 by Lord Morton in 1820. 



The essential facts are discussed by Darwin. 2 In the 

 year 1815 Lord Morton bred a seven-eighths Arabian 

 mare of chestnut color to a quagga. The resulting 



1 Philosophical Transactions, 1821, p. 21. 



2 Darwin, "Animals and Plants under Domestication," 

 vol. I. 



