26 
A few weeks ago I spent a most pleasant and instructive day at 
Brighton with Mr. Merrifield, who was at greit 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 chrysalids within a few degrees of 44deg. F., more 
or less, or if a very low temperature be desired an equable cold of 
88deg. F. is secured by means of a Norwegian cooker; but Mr. 
Merrifield tells me that in 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 vast'y 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 piace 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. 
T 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 chrysalids 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. 
