192 The American Naturalist. [February, 
“These and other general principles have to be considered when we 
attempt to discuss the results which Mr. Merrifield produces by his 
temperature experiments. ; 
* * * “Tf now we apply these principles what do we find? Insects 
which are allowed to pass through their changes at the normal temper- 
ature produce the form which is normal for the district ; that is they 
undergo the normal processes of histolysis and of rehabilitation, and 
in a state of health have at their disposal the energy requisite to give 
them their ordinary wing expanse, scaling and color. Now what does 
Mr. Merrifield do in his experiments? He subjects the pupa to a low 
temperature. This of necessity lowers the vitality of the pupa and s0 
lessens the available energy. The insect therefore does not develop 
under normal conditions, and an abnormality is the result. The insect 
must use what energy it has to build up its vital organs, and fails in 
building up perfectly its secondary tissues—color, scales, wing mem- 
brane, and fails-to in direct proportion to the degree in which the 
vitality is lessened. Below a certain temperature during the period of 
active development the vital force ceases to act at all, and the result 18 
death. Heat, greater than that to which the insect is normally sub- 
jected, instead of lowering the vitality to the lowest ebb at which life 
can be sustained, affects the histolysis and rehabilitation in a directly 
opposite manner. Under its influence the vital processes are carried 
on at express speed. Energy is expended at the fastest rate possible, 
and the tissues are formed without having sufficient time to mature #8 i 
they would under normal conditions, the surplus material is rapidly 
utilized, with the result that as marked an abnormality is produc 
under the one condition as under the other, although in an opposite 
direction. ” 
ntomolo- 
Studying Insect Histories.—That the pursuits of the e pont 
i 
gists are not always so delightful as the chasing of June butte x 
shown by the following extract from a paper recently read by Mr. To 
O. Howard before the Association of Economie Entomologists: j 
gain the clearest and most accurate idea of a life history, the insect m 
be studied under perfectly natural conditions, and not under pee 
which more or less imperfectly simulate the natural ones. There 1s? 
easy road to the most perfect knowledge of habits. It involves yer 
ing through mud and bramble patches; it involves the contan» of 
of sunstroke, and in our southern country the constant pe 
Leptus and Ixodes (itch-mites and ticks) ; it involves constant W pa 
ing and watching and watching, astride the small limb af a fruit 
