72 ON CERTAIN CHARACTERS NOT BLENDING. Chap. XV. 



sweet-pea. The following case is slightly different, but still shows the 

 same principle : Naudin'^^ raised numerous hybrids between the 

 yellow Linaria vulgaris and the purple L. purpurea, and during 

 three successive generations the colours kept distinct in different 

 parts of the same flower. 



From cases such as the foregoing, in which the offspring of the first 

 generation perfectly resemble either parent, we come by a small 

 step to those cases in which differently coloured flowers borne on 

 the same root resemble both parents, and by another step to those 

 in which the same flower or fruit is striped or blotched with 

 the two parental colours, or bears a single stripe of the colour or 

 other characteristic quality of one of the parent-forms. With hybrids 

 and mongrels it frequently or even generally happens that one part 

 of the body resembles more or less closely one parent and another 

 part the other parent ; and here again some resistence to fusion, or, 

 what comes to the same thing, some mutual affinity between the 

 organic atoms of the same nature, apparently comes into play, for 

 otherwise all parts of the body would be equally intermediate in 

 character. So again, when the offspring of hybrids or mongrels, 

 which are themselves nearly intermediate in character, revert either 

 wholly or by segments to their ancestors, the principle of the 

 affinity of similar, or the repulsion of dissimilar atoms, must come 

 into action. To this principle, which seems to be extremely general, 

 we shall recur in the chapter on pangenesis. 



It is remarkable, as has been strongly insisted upon by Isidore 

 Geoflfroy St. Hilaire in regard to animals, that the transmission of 

 characters without fusion occurs very rarely when species are 

 crossed ; I know of one exception alone, namely, with the liybrids 

 naturally produced between the common and hooded crow (Corvus 

 corone and comix), which, however, are closely allied species, 

 differing in nothing except colour. Nor have I met with any well- 

 ascertained cases of transmission of this kind, even when one form 

 is strongly prepotent over another, when two races are crossed 

 which have been slowly formed by man's selection, and therefore 

 resemble to a certain extent natural species. Such cases as puppies 

 in the same litter closely resembling two distinct breeds, are 

 probably due to snperfoetation, — that is, to the influence of two 

 fathers. All the characters above enumerated, which are trans- 

 mitted in a perfect state to some of the offspring and not to others, 

 — such as distinct colours, nakedness of skin, smoothness of leaves, 

 absence of horns or tail, additional toes, pelorism, dwarfed structure, 

 &c., — have all been known to appear suddenly in individual animals 

 and plants. From this fact, and from the several slight, aggregated 

 diiferences which distinguish domestic races and species from one 

 another, not being liable to this peculiar form of transmission, we 

 may conclude that it is in some way connected with the sudden 

 appearance of the characters in question. 



2' * NouTclles Archives du Museum,' torn. i. p. 100, 



