A few weeks ago I spent a most pleasant and instructive day at 

 Brighton with Mr. Merrifield, who was at gre it pains to explain 

 to me his methods, and to point out the results. It will not be- 

 necessary to describe his arrangements for rearing caterpillars on a 

 somewhat wholesale scale ; nor need I dwell upon his apparatus- 

 for raising or lowering the temperature, further than to say that by. 

 extremely ingenious contrivances he is enabled to maintain a 

 temperature steadily between 98deg. and 99 deg. Frhr., or at any 

 other degree of heat he may require ; while with a refrigerator 

 he can keep his cbrysalids within a few degrees of 44deg. F., more 

 or less, or if a very low temperature be desired an equable cold of 

 33deg. F. is secured by means of a Norwegian cooker ; but Mr. 

 Merrifield tells me that iu order to obtain tropical or arctic results, 

 he frequently employs heat or cold to pretty nearly the killing 

 point, when of course the mortality is vasty increased. Some- 

 where about a month is the usual period of exposure to cooling 

 influences, while the hotter temperatures may either be applied 

 until the insects are forced to emerge, or only for a day or two, 

 after which they can be moved to the temperature of an ordinary 

 room and left to themselves. Mr. Merrifield pointed out that the 

 general tendency of heat was to render the markings more or less 

 indistinet, to develop the yellows, oranges, reds, and browns, at the 

 expense of the blacks, whites, and blues, whereas the converse was 

 the case with cold, from which, in addition, the margins of the 

 wings become more scalloped, and some of the markings assumed 

 a different direction to those observed in specimens which had been 

 submitted to the hot treatment. He said, however, that there 

 were occasionally exceptions to these rules for which he was not 

 yet prepared to account — for instance, it seemed to puzzle him why 

 heat should enlarge the spots upon the fore wings of the small 

 copper, while those of the tortoiseshell were diminished by the 

 same process — but, no doubt, with further experience in this 

 interesting kind of investigation, the apparent anomaly will be 

 cleared up. Considerable differences take place on the undersides 

 of the various species operated upon, the enumeration of which 

 would occupy too much of our time ; it will suffice to say that 

 greater uniformity of tint with less definite markings is the general 

 effect of heat, while greater distinctness of markings results from 

 the cooling process. 



I shall now try to explain more lucidly by the aid of these rough 

 figures, the respective changes which take place in the perfect 

 insect, as the consequence of subjecting the cbrysalids to a high or 

 low temperature. 



In the peacock butterfly no great amount of change takes place 

 from heat, but the ground colour becomes a deeper red brown. 



