736 General Notes. [ October, 
preliminary study of some of the relations of climate to the so- 
called “ locust pest” of our Western States. An abstract of my 
. results was published in chapters vi (pp. 203-211) and xv (pp. 
424-432) of the “First Annual Report of the U. S. Entornologi- 
cal Commission for the year 1877 relating to the Rocky Mountain 
Locust, &c, &c.” 
Although the results then arrived at were crude because of the 
paucity of proper material, yet as nothing better has since then ap- 
peared and as the subject has not come to the notice of some who 
might aid in securing further precise data, I will take the liberty of 
bringing the matter to the attention of the naturalists of the 
Academy, to whom we must look for the accurate,determination 
of the thermal constant that we need in order to attain to results 
that may be practicaily useful to the community—premising only 
that I have merely broken the ground for some one else to build. 
My idea is that it would be an important advance toward pro- 
tecting the agricultural districts if we were able at any day to 
say: “ Up to this date the grasshopper eggs have been rapidly (or 
slowly).progressing towards hatching, and they are now within 
five (or other number) days of appearing.” i 
But in order to accomplish this we must know the normal time 
of incubation, which probably must depend principally upon the 
temperature to which its egg is exposed, and upon the peculiarity 
of the locust egg as an organized body having the inherent vital 
power of development. i 
The meteorologist and the biologist must here work in union. 
I have, however, presumed for the first effort to undertake at least 
an approximate solution of both questions, and present here the 
conclusions that are given at greater length in the pages before 
referred tọ. 
© L The Heat of Incubation—It may be assumed that in these 
eggs, as in all similar animal and. vegetable germs, a certain 
definite amount of heat represented by an exposure for a definite. 
number of hours to a uniform, definite temperature will always 
effect the hatching of the young. From the study of the obser- 
vations made by Dr. C. V. Riley, I concluded that at temperatures 
below 50° Fah., the development of the egg progresses very 
„slowly if at all—although the vitality is not destroyed by temper” 
‘ures ° F. J found that the few available observations led 
to the following approximations: 
a, Ata uniform temperajure of 50° F. th gg qi ire 65 E ee y 1560 hours to hatch, 7 
2 ba p 60° te “a 60 s ws 1440 ‘ 
i e A s ’ R e si 5 3 is cs 
4 M Mi “ e 55 « te nian ‘ * 
ETENN i 50 
It may be that at higher temperatures the development pro- 
ceeds at a more rapidly increasing rate ; indeed, one correspondent 
says that at a temperature of 100° F. the eggs hatched out in a 
few hours—but nothing is known as to whether the eggs were 
_ fresh or not, and the observer's name itself is also unknown, there- 
