. The Penycuik experiments. int indications of zebra-likemarkings. Having seen that foals have often stripes at birth whichafterwards disappear, the question of so vital importancein connection with telegony may now be asked : Are thestripes often found on foals due to reversion or atavism ?A direct answer to this question is of course impossible,but an answer sufficiently convincing may be arrived at bythe deductive method. It seems to be admitted that all the breeds of pigeons JI-KGONY AND REVKKSION, 121 have desceiided from the blue rock pigeon {Columba livia),and it has long been known tha
. The Penycuik experiments. int indications of zebra-likemarkings. Having seen that foals have often stripes at birth whichafterwards disappear, the question of so vital importancein connection with telegony may now be asked : Are thestripes often found on foals due to reversion or atavism ?A direct answer to this question is of course impossible,but an answer sufficiently convincing may be arrived at bythe deductive method. It seems to be admitted that all the breeds of pigeons JI-KGONY AND REVKKSION, 121 have desceiided from the blue rock pigeon {Columba livia),and it has long been known that when distinct varieties ofpigeons are crossed^ the young sometimes very closelyresemble blue, rocks. Mr. Darwin refers to a pigeondescended from a red spot and a white fantail on the oneside, and two black barbs on the other. This pigeon washardly distinguishable in its coloration from a wild rock pigeon. Darwin accounted for the occasional resen^blance of cross-bred pigeons to the rock pigeon, by saying they had Fig. Sire of Hybrid shown in Fig. 37- undergone reversion. To quote from Weismann : Darwinwas the first to point out that in cross-breeding, either ofspecies or of mere varieties, characters not infrequentlyappear in the descendants which were not present in theparents; in some of which cases, indeed, it can beproved, and in others shown to be very probable, that they * Animals and Plants/ vol. ii, p. 14. 122 TELliGONY AND REVERSION. have been derived from remote ancestors. * Reversionhas, many think, been proved to occur in pigeons, and it issaid to be very probable in the horse family. In Chile,horses living under conditions not unlike tliose enjoyed bytheir ancestors in Andalusia, are said to have remainedunaltered; whereas in the eastern parts of South Americathe horses some years ago were chiefly dun-coloured withlarge coarse heads. Darwin thought this difference mightalso be due to Mr. T. D. A. Cockerell recentlypointed out that in New Mexico o
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