1868. | _ Darwin and Pangenesis. 297 
main from a change in the reproductive organs of the animal; and 
it appears to us that whilst in his earlier work the author laid too 
little stress upon this obscure phase of his subject, it has haunted 
him throughout the present work; and though he still attributes 
to the external conditions of existence the chief influence in modi- 
fying species (or even varieties), we find his expressions much 
more clear concerning the agency which immediately operates to 
bring about this modification, for he says:—“ The causes which 
induce variability act on the mature organism, on the embryo, and, 
as we have good reason to believe, on both sexual elements before 
impregnation has been effected.” * 
Now this is what may be called a much clearer declaration of 
principle than we have hitherto had from the author; and, 
leaving out of sight the question of the amount of variability 
which can by any means be brought about, we find that virtually, 
according to his views, the nature of the living form is decided 
at its very conception. For, whether the most widely diverging 
characters have been secured, as in the author’s favourite illustra- 
tion, the pigeon, or some “spontaneous” variation has sprung 
up, or some peculiarity has been lost sight of for one or more 
generations and has suddenly reappeared, in every case, and 
especially in the latter, the reproductive elements, or one of them, 
must, according to the author’s views, have been the acting or per- 
petuating agency. In order to account for this marvellous property 
of the germ, the author has supplied us with a provisional hypo- 
thesis, “pangenesis,” and has sought to explain. how the sexual 
elements operate upon the fabric of which they serve as the basis. 
But there still remains a wide subject untouched; and that is, 
whether and in what degree the reproductive organs are affected by 
certain psychical causes, with which neither “conditions of exist- 
ence” nor yet “natural selection” have any immediate relation. 
This phase of the question must, however, be left for a moment 
unconsidered ; and having referred to the crucial difficulty upon 
which we stumble when we regard the mode in which variation 
begins, we must next touch upon that other perplexing problem, 
hybridism, which is considered by the author’s opponents to denote 
its limits, and to stand as an insuperable obstacle in the way of 
the acceptance of his theory. In our former notice of the author's 
works referred to above, we ventured to express the view that 
the phenomenon of hybridism should be regarded in the light 
of an occasional check placed by Providence upon the too rapid 
tendency to vary, which might arise even under the author's slow 
process, and might cause a reversion to the original stock, or a 
confusion of forms, totally subversive of all order in animated 
* “Animals and Plants under Domestication,’ vol. ii., p. 270. 
xy 2 
