Vol. xl. 80 
Mr. E. C. Stuart Baker delivered the following address 
on ‘The Value of Subspecies to the Field Naturalist ” :— 
I must first apologise to my audience to-night for the fact 
that practically all I am about to say has already appeared 
in the ‘Journal of the Bombay Natural History Society,” 
though I then wrote purely from the point of view of the 
Indian Field Naturalist. 
Perhaps, as a preliminary to our discussion, I should state 
what is my idea of a subspecies. It is as follows :— 
A subspecies is a geographical race or variation, differing in 
some respect from the form first described as a species, yet 
linked with it by other intermediate forms found in intervening 
areas. It is essential, however, that the variation before it is 
named shall be proved to be stable within a certain definite 
area. 
From my definition it will be seen that I consider a sub- 
species to be merely a species in the making, and that 
subspecies become full species when Nature, in the course 
of evolution, has eliminated the intervening forms. Some 
naturalists hold that this theory is wrong, and say that in a 
species the germ-plasm is different in itself and in its 
potentialities, and that, therefore, subspecies can never 
become species. I quite agree that in every true species 
the germ-plasm differs from that of every other species, 
but the fact that it is so is only because it has arrived at 
a stage of evolution parallel with the evolution in its colour, 
structural, or other superficial variation from which we 
decide its rank as a species or subspecies. 
The point to be remembered is that evolution in the germ- 
plasm proceeds pari passu with external evolution, though 
. it is not until it has reached an advanced stage that it 
permanently contains the inherent potentialities which pass 
on from one generation to another the external features 
caused by environment. 
Thus a species transferred from its original environment 
may or may not gradually evolve external variations due to 
its new surroundings, but the changes, if any, will be 
assumed by degrees, and as they become fixed, the germ- 
