er 
21 
‘amongst the individuals that they have received separate names, 
‘until by rearing from the egg, or otherwise, they have been proved 
‘to be identical ; it may be that the male bears no resemblance to 
the female, as in tho vapourer, the large lackey, the spotted muslin, 
the clouded buff and many others; it may be that there are two 
‘distinct forms of the male or of the female; this is far commoner 
with the latter sex, examples of which may be observed in the 
dark form of the silyer-washed fritillary, and the pale form of the 
clouded yellow. There may be three separate forms or there may 
be many, as in the case of the buttons, of which latter there are 
-@ large number of named varieties, as will be seen by an examina- 
tion of a collection of them kindly lent by my friend Mr. Purdey. 
Of far rarer occurrence is confusion of the sexual markings. It 
may be that the characters of both are represented on the same 
individual, either laterally or intermingled, or that the male has 
the colours and markings of the female, or vice versa. Another 
curious variation in colour is a shot appearance presenting one 
tint from one direction, another from another; of course, I mean 
‘in an insect which does not ordinarily show this peculiarity. 
A form of variation most intimately connected with the subject 
of this lecture, is that which takes place according to the season of 
‘the year at which the butterfly or moth makes its appearance. Of 
this we have examples in the spring and summer brooded thorn 
moths and mochas, and in the summer and autumn brooded 
comma butterfly. 
Local variations or races are peculiarly interesting, and throw 
much light upon the workings of nature—examples of all these are 
‘shown in Mr. Webb’s selection. Of these we have those which 
inhabit hills, dales, fens, moors, woods, plains, sandhills; northern, 
southern, western, eastern, peaty, chalky, and sandy districts, or 
which are otherwise restricted in their areas of distribution and 
Separated from the parent stock of their species. Especially under 
this heading may be mentioned the island forms, which are 
perhaps the most instructive of all. It has been noticed, too, that 
immigrants and importations exhibit a tendency to variation, if 
they succeed in gaining a foothold on the new soil. Similarly, 
when species are bred at home in our cages generation after 
generation, there is an indication of departure from the type, 
though this is generally in the direction of deterioration. 
When nature has established a variety which has become stable, 
heredity continues the work, and with this material and by 
judiciously crossing different strains, avoiding the typical form as 
much as possible, it is within man’s power to produce other 
variations. In ’67. I suggested that hereditary influences might 
4e turned to account as well by the variety breeder of insects ag by 
