188 THE entomologist's record. 



at disposal. If pigment be an expression of energy, it is clear that 

 under the influence of a cool temperature the vital force of the pupa is 

 not sufficient to cause the pigment material to undergo sufficiently 

 rapid metabolism to produce, in this species, the probably higher 

 colour-development representing prorsa and so levnna only is produced, 

 whilst, on the other hand, under a sufficiently high temperature, the 

 more rapid metabolism perfects the pigment and produces the higher 

 coloration characteristic of prorsa. Here, at any rate, is a simple 

 biological explanation in accordance with the facts at our disposal and 

 not requiring any assumption. In fact, I claim to have given some 

 proof in support of my view, and this, at any rate, has some advantage 

 over the idea of Professor Weismann, who can give no " proof in sujjport 

 of his supposition." 



It is, of course, conceivable, as we have seen in the case of C pMoeas, 

 that the most perfect development may sometimes take jjlace with a 

 low temperature, and that a high temperature (and rapid metabolism) 

 in such cases acts adversely. 



fClENTIFIC NOTES & OBSERVATIONS. 



On wing structure. — After reading Mr. Moffat's interesting paper 

 on this subject, of which some account is given ante, pp. 161-1G2, I 

 wrote to him pointing out that, inasmuch as the energy used up by 

 the muscles in flight would need renewal, especially in those instances 

 where the insect remained on the wing for some time, it followed that 

 there must be circulation of blood through those muscles. I 

 received the following reply from Mr. Moffat which is, I think, of 

 sufficient interest to be submitted to the readers of the Record. — F. J. 



BUCKELL. 



There are many interesting questions yet to be settled in connection 

 with the structure of insects. The need of circulation at the base of 

 the wing is one of these. A mature butterfly's wing is a very unlikely 

 thing to have circulation in it. But there are degrees of dryness ; a 

 wing a week or two old is much drier than one only a day or two old. 

 The joint of the wing seems to be pretty deeply set in the body of the 

 insect; but there must be muscular attachment at the base, and to keep 

 the wing movable, the muscles must have nourishment and moisture. 

 How far up the wing this may extend is the query. I cannot com- 

 prehend circulation without a going and coming ; if blood entered 

 without returning I should expect it to clot and dry up solid, why not 

 to the very base ? I cannot say. The under wings of some Coleoptera 

 (the StaphiJinidae for instance) are jointed in the nervures, so that they 

 can be folded up ; there must, 1 think, be circulation there. Also in 

 the hind-wings of Orthoptera, as the insects fold them ujj like a fan, 

 nothing but a flow of moisture would keep them flexible ; and yet it 

 may be quite im})erceptible. Tliat the fluid is of a life-giving nature, 

 and corres})onds to the blood of the liigher animals, I believe but cannot 

 demonstrate. Mr. Fletcher, of Ottawa, contends that the fluid does 

 enter the nervures. Experimenting with the nervures of a Cicropna, 



