4TT 
And indeed we find it very difficult to understand the 
utility of some of the modifications which take place. 
What advantage can it be, for example, to the insects 
of a particular district to be coloured blue ? And yet,— 
“ In a forest of Southern Brazil, Dr. Seitz found a perfectly circum 
scribed region in which the insects were almost entirely blue ; a few 
miles away from this locality the insects were red, yellow—any colour 
but blue ; but in the particular locality blue was so characteristic 
a tint that, out of twenty butterflies, ten were entirely blue, and the 
remaining ten partially blue. Nor was blue found to be confined to 
the Lepidoptera—the flies and hemiptera were also largely blue.”— 
(Beddard. Animal Coloration, ft. 46.) 
We cannot exactly see what advantage could accrue 
to a tree from the adoption of a fastigate or pyramidal 
growth, and yet the hotter parts of India modify some 
trees in this way. 
“Dr. Falconer informs me that he has seen the English Ribston 
pippin apple, a Himalayan oak, Prunus and Pyrus, all assume in the 
hotter parts of India a fastigate or pyramidal habit ; and this fact is 
the more interesting, as a Chinese tropical species of Pyrus naturally 
has this habit of growth.”—(The Variation, vol. ii., ft. 277.) 
But it would be an immense mistake to infer that, because 
transforming influences are not limited by the principle 
of utility and can therefore put forth unuseful variations, 
all the variations which occur through that agency alone 
are not useful. 
We have seen that transforming influences go on in 
association with the output of individual differences. Now 
it is quite clear that the absence of identity which dis 
tinguishes one individual from another is useful, as those 
will readily admit who have had to live with twins between 
whom it was impossible to distinguish. We cannot doubt 
that it is well that the shepherd should be able to dis 
tinguish each individual sheep which he tends, and that the