1867.] 237 
remark, farther, that this variation, if it be such, can not proceed either from 
locality or food, for, aa regards the former, it is found in all parts of the country, 
and, aa regards the latter, it feeds exclusively (with me) on sallows. Whatever it 
may be, it is certainly a rare insect. For some years past I have had from 300 to 
400 larvEO of cerago and silago mixed together, and I find the proportion between 
the lemon-coloured and the ordinary specimens to be as one in sixty. As I am on 
the subject, I may be permitted to make an observation or two on Dr. Knaggs' 
paper. And first, aa to variation being produced by the action of light, or its 
reverse, I believe this to be an utterly fallacious idea. It obviously can not hold 
good in a state of nature, for it will scarcely be maintained that, of the larvae of the 
same species, one has more Hglit than another ; and, as regards at leaat the sub- 
terranean pupae, all alike are enveloped in the same Cimmerian darkness. Nor can 
I at all give in my adhesion to the " thermic" theory — i.e., that a longer or shorter 
duration of the pupa state has any influence upon the coloration of the future 
imago. I do not exactly understand Dr. Knaggs' "illustration" of "illustraria" 
but I difi'er widely from the conclusion he draws in the following passage: — 
" Again, by a similar agency (retardation or otherwise of the pupal state), we may, 
as a rule, accouut for the greater darkness in tint and markings of many northern, 
and especially Scottish Lepidoptera, as compared with corresponding southern 
types, since many species, double-brooded in the south, are single-brooded in the 
north; and others, which here pass but one winter in the pupa state, are 
apt, in the north, to remain in that state over a second winter, or even for a longer 
period." Now, if this conclusion were well founded, we should find this occur in 
our breeding cages. This, however, we most certainly do not. Take, for example, 
a hundred pupaa of the well-known Eriogaster lancstris. Some will emerge the first 
year, some the second, and so on through five years, and even longer. Yet there 
is not the slightest variation in the intensity of the colouring of these specimens. 
As other, yet, perhaps not such familiar examples, take almost all the species in 
the genua Notodonta. I have occasionally had one or more pup^ of camelina, 
cuculUna, dictma, dromedarius, zic-zac, trepida, chaonia, and dodoncea remain two 
years in that state, but I have never noticed the slightest appreciable difierence in 
colour between the first and second year's specimens. Many similar instances 
could probably be brought forward ; and if, of which I have no doubt, the experience 
of others coincides with mine in this respect, the objection seems to me fatal to 
the " thermic " theory. My own impression has always been, that variations 
(except what Dr. K. aptly terms accidental and hereditary) originate in the larval 
state, and are assisted, at any rate, by soil and food. One memorable instance of 
the latter has occurred to myself, viz., in the case of Cleora lichenaria, a specimen 
of which having been fed upon some orange-coloured lichen, had all the wings richly 
sufi"used with that colour. At the same time I must add that, so far as my own 
experience goes, the intentional supply of diS'erent kinds of food, with the idea of 
producing varieties, is, in almost all cases, a total failure. To conclude, I am much 
of Bouchard's opinion, "that the beast must have lunched ofi" bread and cheese." — 
J. Greene, Cubley Rectoiy, Sudbury, Derby. 
*^* In the above interesting notes I observe that Mr. Greene implies a desire 
for further information respecting "the illustration of illiistrana :" I fear that I did 
