34 
Psyche 
[June 
Grylloblatta campodeiformis Walker (Orthoptera) was chosen 
to represent a cold environment. The grylloblattids generally have 
been collected in late fall and winter, being found in mountainous 
areas on hillsides with coarse rock slides, in deep crevices, under 
stones, or in decaying moss-covered logs and stumps at the margins 
of glacial bogs. On mild winter days a few have been found craw- 
ling on the open snow slopes (Gurney, 1948- — extensive biblio- 
graphy). The nymphal stages are long, in campodeiformis occupy- 
ing five years, with the eggs laid in the sixth year (Ford, 1926). 
Its food consists chiefly of softbodied insects. 
Material and Methods 
A culture of Thermobia that had been maintained at 37.5° C was 
obtained from Mr. John Woodland, of Harvard University. They 
were kept in plastic utility dishes in an incubator at 37.5° C and 
25% R.H., fed on wheat flour and dried beef, and watered from a 
vial and wick. 
The grylloblattids were obtained from Dr. J. H. Pepper, of Mon- 
tana State College. They were kept in plastic dishes at 3° to 5° C 
in a mixture of moss and leaves and fed on pieces of freshly killed 
flies and roaches. 
The oxygen consumption was determined in volumetric micro- 
respirometers (Scholander, 1942), using “Ascarite” to absorb CO 2 
produced, oxygen from “Oxybombs” to fill the reservoirs, and shell 
vials of appropriate size for animal chambers. Constant temperature 
at each level was secured by immersing the respirometers in stirred, 
plastic, water baths, which were immersed in turn in a large, stirred, 
thermoregulated water bath. The animals were exposed to each 
temperature for about 1% hours. At the end of each run the animals 
were weighed and their sex determined. 
For determining the heart rate, each insect was coaxed into a 
short length of glass tubing, the ends of which were then lightly 
plugged with cotton. This confinement prevented violent struggling 
and afforded a clear view of a few cardiac chambers. Of the several 
available grylloblattids, only two adult females proved suitable for 
accurate observation of heart activity through intersegmental mem- 
branes of the anterior abdominal region. Five adult females and 
four adult males of Thermobia were selected. Each of these speci- 
mens was nearly free of scales, while dark material in the crop made 
