6o Experimental Zoology 



The best- known case, and one that Darwin himself beUeved 

 to have been ''perfectly well ascertained," is that of Lord Mor- 

 ton's mare, a full account of which is given in Darwin's "Ani- 

 mals and Plants." A pure Arabian mare was bred to a 

 quagga, and the first offspring was, of course, a hybrid. The 

 second time, the mare was bred to a stallion of pure stock. 

 The colt showed cross markings on the legs, that were said to 

 he much more developed than on colts of pure pedigree. Dar- 

 win thought the evidence sufficient to show that in some 

 unknown way the mother had been affected, either by the 

 sperm of the quagga or by the hybrid embryo in utero, and this 

 effect was again in some unknown way transmitted to the sec- 

 ond offspring. Darwin advanced this case as one of several in 

 support of his hypothesis of pangenesis. 



The statements remained practically undisputed until within 

 recent years. A few years ago Ewart undertook to repeat the 

 experiment, which he was enabled to do by having a small 

 experimental farm placed at his disposal. Careful series of 

 cross-breeding experiments, followed by pure breeding, were 

 carried out. Ewart discusses his results in his book entitled 

 "The Penycuik Experiments," and reaches the conclusion that 

 no clear evidence of infection, if I may so call it, can be pro- 

 duced in this way. He also points out that it is not uncommon 

 for colts, purely bred, to show stripes as distinct as those in Lord 

 Morton's case. Fortunately a picture of this colt is still in ex- 

 istence, and its examination shows that the markings are not 

 more distinct than those that sometimes occur in the case of 

 purely bred animals. There was, then, merely a coincidence, 

 and not a causal connection. 



Bell has given an excellent summary of the evidence in regard 

 to the possible influence of a previous sire, and has carried out 

 a number of experiments on horses and dogs.^ In none of 

 these cases was any influence of the previous progeny or of a 



^ Two other cases were reported to Bell, one for pigeons and the other for a 

 cross between a negro and a white woman. In neither case were the later off- 

 spring, by a father of their own kind, affected by the first union. 



