| Sat = be OS ts A ate 
INSECTS IN 
BY ALBERT JOHN COOK, 
Tue condition of our vertebrate an- 
imals in winter, and also the functional 
condition of their organs, have been well 
studied and are pretty well understood. 
That most of them require more carbon- 
aceous food at this season, as this min- 
isters to the special kind of nutrition 
which supplies animal heat, is a well rec- 
ognized fact. It has long been known 
that some vertebrates hibernate, in which 
state they respire very slowly, and so 
are able to live even though the heart 
does circulate unoxidized blood. 
The functional activity of the organs 
in this case is reduced to the minimum, 
and so nutrition is almost abated, and 
no food is required other than that stored 
up in the adipose tissue. But even 
though these animals do live so slowly, 
with too severe and long continued cold 
they often lose even this little vitality 
and perish. 
Physiologists have determined that 
tissues and organs, whether im situ or 
removed from the body, will maintain 
their vitality for a long time, and often 
indefinitely, if kept in a cold atmosphere, 
though all functional activity is for the 
time held in abeyance. I myself have 
exposed hens’ eggs, while in the process 
of incubation, to a temperature but little. 
above 0° C., until I had good reason to 
believe that the hearts of the embryo 
chicks had ceased to beat. I then re- 
placed the eggs under the brooding hen, 
when with the return of heat came also 
a resumption of development. Very 
WINTER. 
LANSING, MICH. 
likely the same explanation may rightly 
account for the retarded development 
jn many tadpoles that pass the winter 
in animmature state. Most frogs de- 
velop fully in summer, and pass the win- 
ter in a mature state. Yet we not infre- 
quently find tadpoles in mid-winter, or 
large ones at the very dawn of spring. 
If all animals have had a common ori- 
gin (and can any biologist doubt it?), 
we may expect that the phenomena ob- 
served among invertebrates will closely 
resemble the peculiarities which we note 
in our study of the higher forms. 
The effects of cold to stay or retard 
development among insects, though per- 
haps not so long and closely studied as 
have been the same influences as they 
worked to modify development among 
the vertebrates. will be found, I feel quite 
sure, to act in a vcry similar way. 
The winter of 1874-75 was one of the 
most severe ever experienced in the 
northern United States. In the month 
of February of that year, the tempera- 
ture fell below zero of the Fahrenheit 
seale (—17.°8C.), at Lansing, Michigan, 
twenty-one times. The mercury showed 
—20° F. (—28.°9 C.) on eight different 
days, and —30° F. (—34.°4C.) twice. 
Surely this was a good time to study the 
effects of cold upon insect life. 
The codling moth insect (Carpocapsa 
pomonella), as is well known, passes the 
winter, in the larval state, protected only 
by a slight silken cocoon, and some bark 
The 
scale, crevice, or similar Covering. 
