THEORIES OF HEREDITY 87 



The attempts of explaining Telegony itself have also been 

 various. Thus, a storing of the spermatozoa of the first sire 

 in the impregnated female has been assumed, but then birth 

 without a second sire should be possible an occurrence un- 

 known among higher animals. And, further, it is known 

 that the spermatozoa not used up in the fertilization of the 

 female disintegrate and disappear during the period of gesta- 

 tion. Failing the persistence of the germ itself, the influence 

 of the disintegrated germ-substance has been invoked as an 

 explanation. And, lastly, in the " Saturation hypothesis " 

 the mother's constitution is supposed to be influenced by 

 the foetus of the first male, which influence reacts on the 

 next offspring. This implies that characters acquired by 

 the mother from her own offspring are transmitted to her 

 next progeny, and we have, as we shall see in a later chapter, 

 no warrant for such an assumption. 



III.XENIA. 



Under the name of " Xenia," or guest-gifts, certain cases 

 have been described showing the curious phenomenon of 

 the male pollen influencing the substance of the seed, or 

 even the fruit, i.e., parts of the mother- plant, which do not 

 strictly belong to the embryo itself, and which thus receive, 

 as it were, a gift from the fertilizing pollen. To appreciate 

 this fact, we must point out that the surrounding layers 

 of the plant embryo, which form what is commonly called 

 the seed or fruit, are furnished by the maternal tissue of the 

 ovary. Thus, white-grained maize will, when fertilized 

 with pollen from the blue-grained variety, produce white 

 seeds i.e., seeds having a white endosperm (nutritive 

 layer) round the embryo, but also a number of blue- 

 grained seeds having a blue endosperm. It would seem 

 that we have here a direct influence of the male germ on 

 the mother. The only explanation possible for Darwin 

 was to assume a migration of gemmules from the fertilized 

 ovum into the surrounding mother- tissue. Since then, 



