vm 



might be worth while to call attention to a note in our Trans- 

 actions for 1886 (pp. 168-70) which, intermingled with notes on 

 various other subj ects, was likely to be overlooked. It was there 

 shown that the opaque green colour of the larva of Smerinthus 

 ocellat'us was entirely due to the derived pigments stored in the 

 hypodermis cells, the blood being only very faintly tinged. 

 " Before pupation the pigments are withdrawn from the cells, 

 and are dissolved in the (pupal) blood, which therefore possesses 

 a concentrated solution of all the pigments that have passed 

 through this medium during the whole of larval life. ..." 



Prof. Poulton took the opportunity of bringing before the 

 Society Mr. Gerould's kind offer to give the benefit of his 

 experience to English entomologists. He wrote on Jan. 21, 

 1922 :— 



" Colias is very favourable for a physiological analysis 

 of heredity because we know already something about its 

 pigments and can study them spectroscopically and experi- 

 mentally. 



"It is a curious thing regarding melanism in Colias that, 

 while the chemical reaction that produces it is subject to 

 seasonal control and appears in all winter individuals, certain 

 members of the summer brood (cf. ' mutations ' of heiularia) 

 show it, from one of which I now have a few descendants in 

 hibernation. I take it that the chemical reaction is identical, 

 whether brought out by cold or by chromosomal action. 



" If any English entomologist will undertake to breed 

 C. edusa helice I shall be glad to give him the advantage of my 

 experience during the last dozen years with our white variety. 

 Lethal factors or some disturbing causes have given me some 

 interesting though puzzling data, upon which I am now 

 working. Helice, I imagine, from what Harrison and Main 

 published, may be more orthodox." 



The late Dr. T. A. Chapman on germinal " factors " 



AND THEIR INDEPENDENT EXISTENCE AND DEVELOPMENT. 



Prof. Poulton said that Mr. J. H. Gerould in the paper 

 referred to above spoke of the sudden appearance of the blue- 

 green caterpillars as a " new mutation," at once recalling to 

 his mind the opinion he had heard expressed at our meetings 

 by the late Dr. T. A. Chapman, F.R.S., that such sudden 



