53 
REMAKES ON THE KEY. G. HENSLOW’S PAPER. By Charles 
Brooke, M.A., F.R.S., P.R.M.S., &c., Vice-President. 
The writer cannot agree with several of the statements of this paper, more 
especially the following. At page 36 the author says : — 
“ At last a being may be produced so far different from the original 
parents that it would (if its history were unknown) be classed by a naturalist 
as a different genus altogether. This, it will be remembered, has actually 
been done in the case of pigeons.” 
It is probable that no naturalist would ever think of classifying any 
modified pigeon as a separate genus, and the writer is not aware that any one 
has so classified it. ^naturalist might make it a separate species for the 
sake of giving his name to it ; but we all know that the groundless 
multiplication of species has been the bane of natural history. All such 
modifications are properly described as varieties, but not as new species ; 
d fortiori, not as new genera. 
At page 36, line 2 from bottom, the author says : — 
“ Some opponents of his [Darwin’s] views have maintained that the power 
of variation is limited ; if so, the onus probandi rests with them, and no 
proof has ever yet been given. Whereas the possibility of the other view 
has been proved, and the probability of its truth elsewhere derived amounts 
to a moral conviction.” 
If so, it must be admitted that “moral convictions” may rest on very 
slender bases. As regards the statement that “no proof has ever been 
given,” it must be remarked that there is no known instance of a cross-breed 
between animals of different genera ; and between different species of the 
same genus, the offspring is invariably infertile ; for example, the mule. 
It thus appears that hybrid animals are not capable of reproducing their 
own mixed characteristics. This may be assumed to be a provision specially 
ordained to maintain the uniformity of species , and as such, an argument 
against indefinite variation. 
Again, at page 37, the author says : — 
“Now admit the fact of indefinite variation in offspring, &c. 
It is necessary to join issue here; for indefinite variation of offspring is 
not a fact, but an hypothesis, on the validity of which the whole question 
rests. 
Three lines further on Mr. Darwin is quoted as saying : — 
“ The birth of the species and of the individual are equally parts of that 
grand sequence of events which our minds refuse to accept as the result of 
blind chance.” 
But a full and free admission of the truth of this remark does not involve 
a belief in the doctrine of natural selection ; 
