Appendix II. 201 



second sire 1 . And, as he remarks, it would indeed be an 

 extraordinary coincidence if both the well-authenticated cases 

 given in the College of Surgeons Catalogue should have con- 

 formed to his explanation by mere accident. To which I may 

 add that the supposition of such an accidental coincidence would 

 seem to be virtually excluded by the recent occurrence of yet 

 a third case of exactly the same kind. This took place in the 

 Zoological Gardens, where a wild ass of one species was the 

 previous sire to a foal born of another species : the subsequent 

 sire was of the same species as the mother, and his foal, born 

 a few months ago, presented an unmistakable resemblance to 

 the other species. A brief account of the particulars is given 

 by Mr. Tegetmeier in the Field for December 14, 1892. 



So much, then, for the facts. As regards their interpretation, 

 it certainly seems to me that the one which I have supposed to 

 be given by Weismann is less difficult of acceptance than the 

 one which is given by the Lamarckians, as we have seen above. 

 But it also seems to me that the latter explanation is not the only 

 one available under the Lamarckian hypothesis. For, even 

 under this hypothesis, there is no need to assume that the in- 

 fluence of the first sire is exerted on all the somatic tissues 

 of the mother, and that these again reflect this influence on 

 the ovum which is afterwards fertilized by the second sire. 

 A mechanism that could effect all this may well be deemed im- 

 possible. But a much simpler explanation can be furnished 

 by the Neo-Lamarckians, on lines similar to those upon which 

 I have supposed that Weismann's explanation would run. For, 

 on their common supposition that the substance of heredity is 

 particulate, it matters not in the present connexion whether we 

 suppose the particles to be ids or gemmules. Indeed, it is more 

 in accordance with the hypothetical endowments of the latter 

 than of the former, that they should be capable of penetrating 

 the coats of an ovum, if they can survive the disintegration of 

 their containing spermatozoon. Nevertheless, thus far it does 

 not seem to me that any theory belonging to the family of pan- 

 genesis can gain any advantage over the theory of germ-plasm, 



1 Readers who may happen to be acquainted with De Vrie^ impoitant 

 essay on heredity will perceive how well this suggestion fits in with his 

 modification of Pangenesis. 



