34 Mr. F. Merrifield on the effects of artificial 



for the satisfaction of those who may not be conversant 

 with all that has previously been established, it may be 

 expedient to make the observations which follow, and 

 which show the impossibility of ascribing the effects pro- 

 duced to any other cause than the temperature applied. 

 I preface them with the remarks : — 



(1). That the results lose much of their effect in con- 

 sequence of being seen by artificial light. This reduces 

 the effect in nearly all cases, and in some, where colour, 

 and especially yellowish colouring, is concerned, makes 

 a very great difference. 



(2). That in all the Selenias, and in aiitmnnaria, the 

 under side is more affected than the upper ; possibly 

 this may have some significance in connection with the 

 fact that these species, when at rest, expose only, or 

 partly, their under sides. 



(3). That in most of the species experimented on the 

 male is more affected than the female ; this, however, . 

 does not seem to be the case with illnstraria. 



(4). That the more vigorous and healthy the insect 

 experimented on, the more strongly are the effects mani- 

 fested on it. 



Lunaria. — Two families, one of the spring, the other 

 of the summer, emergence ; 24 individuals. The markings 

 of every one of those at the lower temperature are darker 

 than those of any one at the higher temperature. 



Illunaria. — Two families, one of the spring and one 

 of the summer emergence, the former comprising 44 

 individuals, the latter rather more than 100. As to the 

 former, I am not sure that all were from a single pair, 

 but I think it nearly certain that they were so, for they 

 came to me as a single lot, and where similarly treated 

 show a close resemblance in appearance. These two 

 families were exposed to several different temperatures — 

 about 80°, 60°, 51°, and a somewhat lower temperature, 

 viz., that of the open air in winter and spring, emerging 

 about April, when the temperature averaged little over 

 42°. Unless where the range of temperature was such 

 as to cause little difference in colouring, which was the 

 case as between some of the classes at the lower ranges, 

 every individual which was kept at the lower temperature 

 is darker than any which was kept at the higher tem- 

 perature, with the excejition of a few females, and these 

 form no exception, if the under sides are looked to. 



