138 [May 



specimens subjected to the lower temperatures being generally darker, and the blue 

 crescents were more intense in colour. In conclusion, Mr. Merrifield said a tempera- 

 ture of 47° seemed to stunt the size, and produced a large proportion of cripples, 

 and higher temperatures than this seemed more conducive to health and vigour ; it 

 had been suggested that the results he had obtained were attributable to the un- 

 healthy conditions to which the pupae were exposed, but this was not at all a correct 

 explanation, in the 172 specimens he exhibited ]50 were not cripples, extreme 

 temperatures produced crippling, but moderate temperatures were quite sufficient to 

 account for the extreme difference of colouring. Mr. Fenn said he had since 1859 

 paid great attention to the earlier stages of Lepidoptera, and he assumed that varia- 

 tion was either natural or artificial ; natural variation might be again divided into 

 three nearly equal causes, viz., heredity, moisture, and natural selection ; in artificial 

 variation the causes might generally be said to be abnormal or diseased, by the term 

 disease he meant a general weakening of the constitution by unnatural influences ; 

 the least deviation from natur il conditions might lead to variation. IE. autumnaria, 

 one of the species relied on, Mr. Fenn had had considerable experience in breeding, 

 and in the series he exhibited there were many paler and many darker than any 

 shown by Mr. Merrifield, and the larvae and pupae had been kept under usual 

 conditions, and the greater proportion of them fo lowed the parent forms. In 

 conclusion, he said that such variation as was shown by Mr. Merrifield was practically 

 impossible in a state of nature, unless it was the result of disease. Messrs. Weir, 

 Adkin. Tugwell, Carrington, Dobson, Barrett, and Tutt continued the discussion, 

 the last named gentleman following Mr. Fenn in attributing the variation to disease, 

 and that to a large extent it was caused by preventing the proper development and 

 formation of the colouring pigment ; he thought the action of temperature was 

 indirect, and produced variation by interfering with the normal development. Mr. 

 Merrifield agreed with many of Mr. Fenn's observations, and thought most of them 

 were consistent with the results obtained in his experiments as reported by him ; in 

 any case, there could be no doubt that in the species principally operated on by him 

 temperature applied in such moderation as not to affect the healthy appearance of 

 the insect produced with great uniformity conspicuous differences in colouring. 

 There were other species in which no considei-able effect was pi'oduced, unless the 

 temperature was so extreme as to cause a certain amount of crippling or imperfect 

 development. The Meeting closed with a vote of thanks to Mr. Merrifield, proposed 

 by Mr. Fenn and seconded by Mr. Jenner Weir. 



April 14ih, 1892. — The President in the Chair. 



Mr. R. South exhibited Aretia Caia, L., and read notes on the variation in this 

 species. Mr. C. Gr. Barrett, long series of Noctuaf estiva, Hb., from all parts of the 

 British Isles, and expressed an opinion that the so-called Scotch N. conflua was a 

 form of N.festiva. Mr. R. Adkin and Mr. Tugwell likewise exhibited this species, 

 and a discussion ensued as to the identity of f estiva with conflua. Mr. Barrett also 

 exhibited a specimen of Notodonta hicolor, Hb., belonging to Major Still, and taken 

 in Devonshire, as well as varieties of Rhopalocera from Mr. Sydney Webb's collection, 

 Mr. R. Adkin, Phihalapteryx lapidata, Hb., and P. vittata, Bork., and contributed 

 notes. Mr Lewcock, varieties of Silpha atrata, from English, Scotch and Irish 

 localities, and made some observations thereon. — H. W. Bakkek, Son. Secretary. 



