67 
sary and important part), yet if a person’s pursuit of entomology stops 
short at collecting, he is about as much a scientific entomologist as a 
butcher is a comparative anatomist or a physiologist. In the“pursuit 
of his study the entomologist will find a great part of his material in 
the living insects which are the objects of his tender care and solicitude. 
The habits of species may be well known, but what relationship do 
these habits bear to the environment of the species ? The colours of 
larvse may have been well-described, but what is the meaning of a 
particular mark or a particular spot? The differences between two 
closely allied butterflies may have been very carefully worked out, but 
what has brought about these differences ? Two different forms of the 
same insect may be known, but what is the cause of the difference ? 
The polymorphism of a moth is exceedingly interesting, but what 
inherent factor has produced the polymorphism ? And here even the 
best stop at present. What are the inherent factors that produce, 
determine and guide the forces which result in variation? We theorise; 
we think that we have solved a puzzle, only to find that some one 
detects an error in our data, a defect in the foundation of our theory, 
and down comes the super-structure to the ground. But destructive 
criticism is much easier than the formulation of a new theory to put in 
the place of what we destroy. Nevertheless, we find, in spite of the 
searching criticism to which every new theory is subjected, that a great 
deal of solid headway has been made. When a man observes a 
phenomenon, his first question should be—What is the cause of it? 
When he attempts to answer the question and starts his theory he must 
ask himself —Can I knock a hole in the bottom of it ? If he cannot, and 
if other scientific students cannot, then the theory must stand as an 
exjidanation of the fact until something better can be put in its place. 
This, in truth, is the basis of all scientific study, which makes men, if 
they will, find— 
“ Books in the running brooks, 
Sermons in stones, and good in everything.” 
The excellence of British collections of Lepidoptera has alwaj^s been 
conceded, and the extent of the insect fauna of the British Islands, in 
comparison with that of other countries of equal or greater area, is very 
noticeable. The known Tortrices of the Palsearctic area, total up to 
about 650; of these, above 350 are British. Almost 50 per cent, of 
the known Pahearctic Tineina (taking this group in its old and widest 
sense) are to be found, and so on. We have in Britain two-thirds of 
the number of insects to be found in the whole of Germany and 
Switzerland combined. It is not at all difficult to understand 
why this is so. No country in the world of equal area presents the 
same diversities in its geological characters as do the British Islands, 
and I need not point out how intimate is the connection between the 
geology of a country and its flora, and between the flora and the insect 
fauna. The varying geological conditions give us a flora, large both 
in the number of genera and relatively in the number of species, and 
this is sufficient to account for the fact that we have so large a percent¬ 
age of the Pahearctic insects existing in our midst. This fact helps to 
explain why the insularity of British entomologists has never been so 
fatal to their scientific aims as would have been expected, and at the 
same time, why a thorough study of the British fauna has often formed 
an admirable education for those who have afterwards made their names 
as entomologists or naturalists of the world. 
