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 silver-washed fritillary, and tbe 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 

 a large number of named varieties, as will be seen by an examina- 

 tion of a collection of them kindly lent by my friend M r. 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 estabhshed 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 

 be turned to account as well by the variety breeder of insects as by 



