PRESIDENT’S ADDRESS. 13 
differences. Such small differences are often mere ephemeral effects 
of conditions of life, and as such are not transmissible; but even small 
differences, when truly genetic, are factorial like the larger ones, and 
there is not the slightest reason for supposing that they are capable 
of summation. As to the origin or source of these positive separable 
factors, we are without any indication or surmise. By their effects 
we know them to be definite, as definite, say, as the organisms which 
produce diseases; but how they arise and how they come to take part 
in the composition of the living creature so that when present they are 
treated in cell-division as constituents of the germs, we cannot con- 
jecture. 
It was a commonplace of evolutionary theory that at least the 
domestic animals have been developed from a few wild types. Their 
origin was supposed to present no difficulty. The various races of 
fowl, for instance, all came from Gallus bankiva, the Indian jungle- 
fowl. So we are taught; but try to reconstruct the steps in their 
evolution and you realise your hopeless ignorance. To be sure there 
are breeds, such as Black-red Game and Brown Leghorns, which have 
the colours of the jungle-fowl, though they differ in shape and other 
respects. As we know so little as yet of the genetics of shape, let us 
assume that those transitions could be got over. Suppose, further, as 
is probable, that the absence of the maternal instinct in the Leghorn 
is due to loss of one factor which the jungle-fowl possesses. So far 
we are on fairly safe ground. But how about White Leghorns? Their 
origin may seem easy to imagine, since white varieties have often 
arisen in well-authenticated cases. But the white of White Leghorns 
is not, as white in nature often is, due to the loss of the colour-elements, 
but to the action of something which inhibits their expression. Whence 
did that something come? The same question may be asked respecting 
the heavy breeds, such as Malays or Indian Game. Each of these is a 
separate introduction from the East. To suppose that these, with their 
peculiar combs and close feathering, could have been developed from 
pre-existing European breeds is very difficult. On the other hand, 
there is no wild species now living any more like them. We may, of 
course, postulate that there was once such a species, now lost. That 
is quite conceivable, though the suggestion is purely speculative. I 
might thus go through the list of domesticated animals and plants of 
ancient origin and again and again we should be driven to this 
suggestion, that many of their distinctive characters must have been 
derived from some wild original now lost. Indeed, to this unsatisfying 
conclusion almost every careful writer on such subjects is now reduced. 
If we turn to modern evidence the case looks even worse. The new 
breeds of domestic animals made in recent times are the carefully 
selected products of recombination of pre-existing breeds. Most of the 
