2g6 THE GERM-PLASM 



taining the group of ids which controlled, or was ' dominant ^ 

 at, its ontogeny, but many other combinations of ids may be 

 contained in its germ-cells. 



In this connection I should like to call attention to an inter- 

 esting essay which appeared when I had almost finished putting 

 the final touches to my manuscript. It bears the pseudonym 

 ^ Josef Miiller'* on the title-page, and contains in particular an 

 attempt to solve the problem discussed above. The ingenious 

 author, who is accurately acquainted with the subject he treats 

 of, doubts my hypothesis of the ids, but endeavours to account 

 for the very remarkable disappearance of the hereditary ten- 

 dencies of one of the parents in ' pseudo-monogonic ' heredity 

 by supposing that the two homologous primary constituents 

 {' Anlage ') of the father and mother respectively take part in a 

 struggle ('gamomachia '), which results in the destruction and 

 complete ' consumption (' gamophagia ') of one of them. In 

 principle this explanation of the problem approaches very 

 closely to the solution I have attempted to give, and though I 

 consider the fundamental idea it contains to be correct, I do 

 not think that we may suppose, as the author does, that this 

 struggle occurs at the beginning of ontoge?iy. Basing this con- 

 clusion on a statement made by Oscar Hertwig, from which it 

 is conceivable that the homologous ^ primary constituents ' of 

 the parents unite in the process of fertilisation, he further con- 

 cludes that the struggle takes place during this union, and leads 

 to the destruction of one of them. Apart from the fact that the 

 paternal and maternal idants remain separate during fertilisation, 

 it seems to me that a large number of the phenomena of heredity 

 contradict the idea of such a union and subsequent struggle. 

 The reappearance of the 'destroyed' primary constituent in the 

 germ-cells — and consequently in the next generation, the phe- 

 nomena of reversion — which show that every primary constitu- 

 ent must be present in more than two variants in the germ-plasm, 

 and, finally, sexual dismorphism, the occurrence of a large 

 number of very different hermaphrodite structures in certain 

 cases, and sexual reversion, — all tend to disprove such a 

 hypothesis. Moreover, apart from my theory of the ids, I 

 believe that this struggle of the homologous primary constituents 



* Josef Miiller, ' Uber Gamophagie, ein Versuch zum weiteren Aufbau 

 der Theorie der Befruchtung u. Vererbung," Stuttgart, 1892. 



