42 
Psyche 
[June 
possible exception is the hive bee, which increases its respiratory 
rate and activity on either side of a preferred temperature range 
of 20° to 25°C (Woodworth, 1936). It was expected that Thermobia 
and Grylloblatta might prove to be exceptions to the rule. How- 
ever, the slopes of the two oxygen consumption curves are practically 
identical (2.7 and 2.8) ; in the intermediate temperatures their 
respiratory rates overlap; and their Q 10 ’s are in the same range as 
those of all insects previously reported. They extend the general 
metabolism — temperature curve, and Thermobia most amazingly so. 
They are similar to other insects in that they are evidently strictly 
poikilothermal and utilize only supplementary insulation to offset 
unfavorable temperatures. 
The temperature characteristics obtained over the intermediate 
temperature ranges agree essentially with previous work on arthro- 
pods concerning heart activity and other rhythmic neuro-muscular 
processes. Comparison of the two sets of data here presented, plus 
the fact that the heart rate temperature characteristics are not typ- 
ical of catalyzed oxidative reactions, seem to support the view that 
respiration is not the fundamental process determining heart rate 
(see Fries, 1926, for further discussion and bibliography). The 
temperature characteristics obtained from the oxygen consumption 
curves are typical values for cellular respiration. 
What is now needed most urgently is a thorough study of the 
biology of Grylloblatta, which would provide a firmer ground for 
the interpretation of data such as here presented. How does the 
insect manage to stay within the narrow range of —5° to 18°C in 
nature? Does it escape the inevitably severe sub-zero temperatures 
of its habitat by crawling into deep, rocky, fissures, or in and around 
roots and in humus where the temperature may remain close to 
freezing? Is it possible, however unlikely, that the paralysis pre- 
ceding death at the extremes of its range may be a hibernation state ? 
What relationship exists between the length of the nymphal stages 
and the low temperature range? What intra- and interspecific var- 
iations in temperature responses occur and how do these relate to 
distribution? A clue to the answer to the last question has perhaps 
been suggested by Campbell (1948). He reported that a form of 
Grylloblatta found at Kamloops, under conditions less severe than 
those of the Canadian Rockies and Montana, did not succumb to 
warmth as easily as typical campodeiformis usually does. This may 
represent lack of uniformity in temperature preferenda, but it 
