﻿42 THE ENTOMOLOGIST. 



(see ' Entomologist,' xxxiii. p. 90), but I should warn them not to 

 subject " emeralds " to the treatment, as the tints are thereby 

 spoiled ; other colours seem to be quite resistant. — W. S. Gilles, 

 E.I.C., F.C.S. ; Booking, Braintree. 



Further Note on Formaldehyde. — The interest — for I have 

 received several communications on the subject — taken in my note in 

 the ' Entomologist ' of December last on the use of formaldehyde, 

 prompts me to enclose a few further remarks which may be of 

 interest to Mr. Kershaw and others. Solution of formic aldehyde or 

 formaldehyde is synonymous with formalin, which is a trade term. 

 It is usually sold in forty per cent, solutions, and should be kept in a 

 well stoppered bottle, in a cool place, protected from light. Solutions 

 of greater concentration than thirty-eight per cent, tend to crystallize 

 out into the solid polymer, paraformic aldehyde. This is the usual 

 form (mixed with a little paraffin wax) used for disinfecting houses, 

 &c., by means of the "formalin lamp." In the concentrated form it 

 is a powerful caustic, and should be handled with care. A one per 

 cent, solution kills most micro-organisms, and a four per cent, 

 solution is used as a hardening agent for microscopical purposes in 

 pathology. It is incompatible with ammonia and fatty bases. From 

 the above figures it is obvious that one can easily make a five or 

 ten per cent, solution of formaldehyde in ether, in order to try Mr. 

 Kershaw's excellent suggestion of hypodermically injecting insects. 

 So far, I have not tried this method, because the vapour has hitherto 

 given such good results with so little trouble, but I intend to at the 

 first opportunity. One point occurs to me, viz. should the injection 

 be done while the insect is still soft, or after the "initial set"? 

 When soft, the needle would slip in easily, and there would be less 

 risk of damage to the specimen, but the ethereal solution W'Ould 

 probably permeate better when the insect was dry. Experience, 

 however, will show. — Winston St. A. St. John, M.E.C.S., L.R.C.P. ; 

 Derwent House, Derby. 



L^LiA ccENOSA, &c., AT WiCKEN. — With reference to Mr. G. B. 

 Kershaw's notes on Lcelia ccenosa at Wicken (' Entomologist,' 

 January, 1915, p. 20), it may be as well to state, for the benefit of the 

 younger generation of lepidopterists, that the last record of the 

 occurrence of the species in Britain may be found in pages 229 and 

 230 of the ' Entomologist ' for 1879. In that year I took three speci- 

 mens on the night of July 26th, and two more two or three nights 

 later. Mr. Kershaw is quite right in saying that I exchanged those 

 five specimens, still unset, for as many Nascia cilialis ; but it ^vas not 

 with the late Solomon Bailey, but with the late Albert Houghton. 

 Since then that exchange has been the greatest entomological regret 

 of my life ! But at the time my then very short series of ccenosa 

 was complete, and as cilialis was in those days considered rare, and 

 a great desideratum with me, I let them go without any hesitation, 

 never supposing there was even a possibility that ccenosa might never 

 again be recorded in Britain. The five specimens were all very fine 

 males, bigger than any I possess even now. Houghton sold them to 

 Mr. W. H. B. Fletcher, in whose collection they still remain. The 



