ON SPECIES AND RACES, AND THEIR ORIGIN 391 
Mr. Darwin’s chapter on the struggle for existence, as affording ample 
satisfactory proof that such adequate natural causes do exist. 
There can be no question that just as man cherishes the varieties 
he wishes to preserve, and destroys those he does not care about; so 
nature (even if we consider the physical world as a mere mechanism) 
must tend to cherish those varieties which are better fitted to work 
harmoniously with the conditions she offers, and to destroy the rest. 
There seems to be no doubt then, that modifications equivalent in 
extent to the four breeds of pigeons, might be developed from a 
species by natural causes ; and, therefore, if it can be shown that these 
breeds have all the characters which are ever found in species, 
Mr. Darwin’s case would be complete. However, there is as yet no 
roof that, by selection, modifications having the physiological character 
of species (2.2, whose offspring are incapable of propagation, zéer se) 
have ever been produced from a common stock. 
No doubt the numerous indirect arguments brought forward by 
Mr. Darwin to weaken the force of this objection are of great weight ; 
no doubt it cannot be proved that all species give rise to hybrids 
infertile, z¢er se ; no doubt (so far as the speaker’s private conviction 
went), a well conducted series of experiments very probably would 
yield us derivatives from a common stock, whose offspring should be 
infertile, zz¢er se: but we must deal with facts as they stand; and at 
present it must be admitted that Mr. Darwin’s theory does not 
account for all the phenomena exhibited by species ; and so far, falls 
short of being a satisfactory theory. 
Nevertheless the speaker expressed his sense or the extremely 
high value to be attached to Mr. Darwin’s hypothesis ; and, avowing 
his own conviction that the following it out must ultimately lead us 
to the detection of the laws which have governed the origin of species, 
he concluded his discourse in the following words, which he wishes to 
be added in full to the very brief preceding account of his view of 
Mr. Darwin’s argument .— 
“T have endeavoured to lay before you what, as I fancy, are the 
turning points of a great controversy ; to render obvious the mode in 
which the vast problem of the origin of species must be dealt with ; 
and so far as purely scientific considerations go, I have nothing more 
to say. But let me beg you still to listen to a last word respecting 
the unscientific objections which I constantly hear brought forward 
on the part of the general public, against such doctrines as those we 
have been discussing. For this is a matter upon which it is of the 
utmost importance that men of science and the public should come to 
an understanding. I have heard it said that it is presumptuous for 
