GENERAL PRINCIPLES OF BREEDING. 73 



the next are correspondingly reduced. Yet it is evident 

 that this may occur, and, as a matter of fact, we find cases in 

 which the bearing of a mulatto by a white woman has 

 affected the appearance of some of her later children by a 

 white man. But such a result is very exceptional in the 

 human family, and this is precisely what is to be expected if 

 our explanation of its cause is the right one. 



It has been objected that a similar phenomenon has been 

 observed in pigeons, and that in them this law of cell-inocu- 

 lation could not take place. But this is, manifestly, a mis- 

 take. The eggs of birds are impregnated even as high up as 

 the ovary. Says Owen: "In coitu spermatozoa enter the 

 cloaca and penetrate the oviduct, ascending to the ovarium." 

 The impregnated egg goes on enlarging by subdivision of its 

 cells in the ovary and upper end of the oviduct, and, being 

 as yet destitute of shell, its cellular structure is in direct 

 contact with the maternal tissues. There is, therefore, a 

 similar opportunity for cell-inoculation as in the mammal, 

 although more limited in duration. 



But our manner of viewing this subject is still further sup- 

 ported by a series of. phenomena observed in hybridized 

 flowers. Darwin quotes instances from Wiegmann, Gartner, 

 Berkley, and others, to show that where the flowers of the 

 white pea had been fertilized by pollen of the blue pea the 

 resulting pods contained a mixture of blue and white peas. 

 And this coloration was not confined to the cotyledons of the 

 seed (the true embryo), but extended to the skin as well. 

 More remarkable still: Mr. Laxton, of Stamford, ''fertilized 

 the tall sugar pea, which bears very thin, green pods, becom- 

 ing purplish-brown when dry, with pollen of the purple- 

 podded pea, which, as its name expresses, has dark, purple 

 pods with thick skin, becoming pale, reddish-purple when 

 dry." 



Mr. Laxton has "cultivated the tall sugar pea during 

 twenty years, and has never seen or heard of its producing 

 a purple pod; nevertheless, a flower fertilized by pollen from 

 the purple pod yielded a pod clouded with purplish red, 

 which Mr. Laxton kindly gave to 'me. A space of about 

 two inches in length, near the extremity of the pod, and a 



