3l6 THE GERM-PLASM 



d, f, were dominant, and the germ-plasm in the ontogeny 

 of the mother consisted of the idants /, k, /, m, ;/, o. p, q. of 

 which i, 1. n, o essentially determined her type. If the reduc- 

 ing division then resulted in an egg-cell containing the idants 

 k, m, p, q, and a spermatozoon was formed which contained 

 the idants c, e, g, h, and these came together in the process of 

 amphimixis, the resulting germ-plasm would certainly contain 

 characters of both families, but it could not possibly produce 

 the type either of the father or mother, or a mixture of both. 



I have already discussed the question of reversion of the 

 child to one of its four grandparents in detail, and need not 

 return again to this point. I should, however, like to call 

 attention to the fact that, theoretically, a child can never exhibit 

 a combination of the types of two of its g?'andparents, simply 

 for the reason that at least half of the idants of a germ-plasm 

 determine the type of the child, the germ-plasm of which can 

 only contain one quarter of the idants of two grandparents. 

 An exception to this rule could only occur in cases of close 

 interbreeding, in which both grandparents in part contained 

 the same idants. 



No case has, however, ever come before my notice in which 

 a child bore no resemblance to its parents and yet exhibited a 

 combination of the types of that of two of the grandparents. 



3. Reversion to the characters of ancestors far re?noved in 

 animals and plants. 



We will now consider the question of reversion to reinote 

 ancestors. Cases of such reversion are so well known through 

 Darwin's researches, that a more detailed description of the 

 mere facts might almost be considered superfluous. But 

 such a description is nevertheless necessary, and I must even 

 express the opinion that the facts have not been so accurately 

 investigated from all points of view as is desirable in order that 

 a theoretical explanation of them may be arrived at. Darwin 

 was the first to point out that in cross-breeding, either of species 

 or of mere varieties, characters not infrequently appear in 

 descendants which were not present in the parents, in some of 

 which cases, indeed, it can be proved, and in others shown to 

 be very probable, that they have been derived from remote 

 ancestors. Mules, for instance, sometimes exhibit distinct 

 stripes, like those of the zebra, on the fore-legs and shoulders, 



