834 THE ENTOMOLOGIST. 



temperature as that which I found necessary to produce my 

 high temperature forms, that is, 80° or upwards ; and it is here 

 that the argument fails. Mr. Frohawk says, " Considering the 

 vast numbers I saw on the same piece of ground at the same 

 time, all having evidently been bred close by, they must 

 necessarily all have been subjected to high temperatures during 

 their various stages, and especially while in the pupa, as the 

 temperature, both day and night, remained so high for weeks 

 previous to and at the time of emergence ; many were in rich 

 condition, having evidently only just emerged." As it is a 

 question of " my views," I need not concern myself about the 

 stages anterior to the pupal stage, because my views, as recorded, 

 are that it is in the pupal stage, and more especially in a rather 

 late portion of it, that the general colouring of G. phlceas is 

 affected by temperature, It is quite true that the summer was a 

 remarkably hot one, but a conclusion that therefore the summer 

 pupse of 1893 were exposed for all or even the greater part of 

 their pupal existence to a tempex*ature averaging 80° to 90° would 

 be quite an erroneous one, as I proceed to show. It is to be in- 

 ferred, from the passage I have quoted, that the specimens captured 

 on the 5th and 6th September, — at all events those of such quality 

 that they were preserved — were mostly fresh specimens, i. e., had 

 but recently emerged. According to my recorded experiments, 

 the temperature from the 5th September, back for about twenty- 

 two days, would cover the whole period that the captures were in 

 pupa. I reject the 4th and 5th September, because I have found 

 the general colouring practically fixed before the last day or two 

 of the pupal period ; this leaves twenty days, counting back from 

 the 3rd September, of which about the last twelve would, 

 according to experiment, cover the most sensitive period It 

 may surprise those who are not in the habit of comparing their 

 general impressions of a warm period with a thermometric record 

 to learn that, during the twenty days referred to, the average 

 of the mean daily temperature in the south-east of England was 

 less than 65°; and that during the critical twelve days it was 

 only about 60°. I do not know exactly where the captures were 

 made, but assume they were in North Surrey, near suburban 

 London. I have therefore not limited myself to the sea-coast 

 temperature of my own residence, Brighton, but have also 

 obtained that of the Kew Observatory, and through the kindness 

 of friends have been supplied with other local records of the 

 periods in question, from the 15th to the 22nd August, and from 

 the 23rd August to the 3rd September. They work out as 

 follows (see opposite). 



Mr. G. von U. Searle, who kindly supplied me with the 

 West Kensington figures, explained that for local reasons his 

 figures would be rather higher than those for the open country ; 

 and Mr. Oswald Latter, who kindly furnished me with the 



