EVOLUTION 1047 



deciduous trees. This is a peculiar case and may be interpreted as 

 follows: the original imports underwent a gradual constitutional 

 change — some modification of their metabolism; this might affect 

 the constitution of the seed during the period when it was still part 

 and parcel of the parent's body. The change in the metabolism might 

 result in the affected seeds developing into evergreens, though the 

 direct environmental influence would work in the opposite direction. 

 It is unfortunate that the observations were not carried further. 



Another interesting case, reported by Zederbauer, concerns a 

 Turkestan relative of the Shepherd's Purse {Capsella hiirsa-pastoris). 

 It has apparently spread from the low country to the uplands, and 

 the specimens growing at the higher altitudes were smaller than 

 those below, with pink instead of white flowers, and tending to be 

 xerophytic. In this there is nothing very peculiar, nor in the fact 

 that seeds of lowland forms sown in the upland develop into smaU 

 plants with pink flowers. But the striking observation was that 

 when the upland forms were transplanted to the low country, they 

 kept their characters, except the xerophytic leaves. But again there 

 is need for an extension and prolongation of the experiments. 



A famous case, often referred to, is that of the wild horses of 

 the Falkland Islands, which Darwin studied on his Beagle voyage 

 (1833). He says that the horses and also the cattle were introduced 

 by the French in 1764. Whereas the cattle are large, the horses are 

 small, and Darwin speaks of them as "having degenerated". "They 

 have lost so much strength that they are unfit to be used in taking 

 wild cattle with the lasso: in consequence, it is necessary to go to 

 the great expense of importing fresh horses from the Plata. At some 

 future period the southern hemisphere probably will have its breed 

 of Falkland ponies, as the northern has its Shetland breed." Darwin 

 seems to have regarded the degeneration of the Falkland Islands 

 horse as due to the humid climate and the lack of suitable food; 

 but it is difficult to believe that marked changes were effected 

 between 1764 and 1833. It would be necessary to know more about 

 the horses originally imported. 



Various statements have been made in regard to changes brought 

 about in the hair of sheep, goats, cattle, sheep-dogs, and even cats, 

 when these animals are taken to a more rigorous climate. It is said 

 that the hair becomes longer and thicker, which would be a useful 

 adaptation. But there is a lack of precision in these statements, 

 and a lamentable absence of measurements. It would be useful to 

 know what additions were made to the coat after the climatic 

 change; whether the offspring, exposed to the cold from birth, 

 showed further additions ; and the character of the fur in the grand- 

 offspring. As regards modifications, no inference can be drawn from 

 the occurrence of adaptive peculiarities, unless the history is known. 

 This applies to a case quoted by Weismann (1904) from Milne- 



