Weismannism tip to date (1893). 127 



detail is concerned, I do not see how it can do so 

 to many others. For the case which he considers is 

 that of Cystisus adami, where a bud of one species 

 of Laburnum having been inserted in the wood of 

 another produced a shoot which presented inter- 

 mediate characters ; and these have ever since been 

 propagated by cuttings. Weismann's interpretation of 

 the facts here is, " that they were due to an abnormal 

 kind of amphimixis, so that the idants of both species 

 were combined in the apical ceil of the first shoot l ." 

 Now, although this explanation may well apply to 

 a case of graft-hybridization by means of buds, it 

 obviously cannot do so to any case where hybridization 

 is produced by the grafting of woody tissues. For 

 here there is no " apical cell " in the question ; and 

 therefore the difficulties which I have adduced on 

 page 82 remain. Possibly Weismann may dispute 

 the fact of hybridization in any of these cases ; but, 

 as he has not expressly done so, I will not go into 

 the question of evidence 2 . 



One important addition to this side of Weis- 

 mann's system has been made in order to meet 

 the class of difficulties which are presented by the 

 apparent inheritance of certain climatic variations, as 

 already mentioned on pp. 67-8. For example, his 

 own butterflies seemed to render definite proof of 

 somatogenetic variations caused by changed con- 

 ditions of life being transmitted to progeny. There- 

 fore, it will be remembered, Weismann candidly 

 admitted, " even now I cannot explain the facts 

 otherwise than by supposing a passive acquisition of 



1 The Germ-plasm, p. 342. a See, however, p. 83, note. 



