142 Field Museum of Natural History — Zoology, Vol. XI. 



is not thoroughly understood. Its marked characteristics are abnor- 

 mally low bodily temperature with nearly suspended respiration; 

 heart action much reduced with consequent slowing of the circulation. 

 Animation is suspended to a degree resembling death and the appar- 

 ently dead animal soon becomes actually so, if taken from its hole 

 and exposed for any length of time to a temperature a few degrees 

 below that of freezing. This strange physiological condition enables 

 certain animals, which without some such provision of nature would 

 otherwise perish from lack of food, to pass the winter sleeping in their 

 holes or burrows in latitudes where the ground is frozen and covered 

 with snow and ice for several months in the year. 



Regarding the hibernating of the Striped Gopher or Prairie Squirrel, 

 Kennicott writes, ''At the approach of severe cold, in autumn, the 

 prairie squirrel retires to its burrow, entrances to which are tightly 

 closed with earth to exclude the frost. In the large nest of grass he 

 curls himself up, with his head against the abdomen, and falls into a 

 state of torpor, out of which he does not awaken until the return of 

 warm weather in spring. In this state, he takes no nourishment 

 whatever, nor does he move. 



"If cut or bruised he exhibits no signs of feeling; and to all exter- 

 nal appearances seems dead. Respiration and the circulation of the 

 blood are carried on very imperfectly; but slight oxygenation of the 

 blood takes place, and little heat is generated — the body being cold. 

 There is no secretion or excretion, and very little waste of tissue 

 occurs, and thus the necessity of food is obviated. From this state he 

 is at once revived to activity by the simple application of heat. Placed 

 in the cold he again becomes torpid. It is to be observed that the 

 species, which passes the winter thus in profound torpor, if removed to 

 a warm climate, or if kept in a warm room, will remain active during 

 winter. Thus we see how, in the perfect laws of Nature, it is or- 

 dained that hibernating animals shall fall into this state of torpor only 

 when they would suffer from cold and want of food, if active."* 

 {I. c, pp. 73-74). 



Concerning the condition of this animal during hibernation, the 

 report of Dr. P. R. Hoy is of interest. He writes, ''During activity 

 the gopher's pulse is 200, respiration 50, temperature 105. . . . 

 On the 15th of December, the gopher being thoroughly torpid, tem- 

 perature of the room 45, gopher rolled up like a ball, no visible 

 evidence of life, I opened the abdomen and inserted the bulb of a 

 thermometer which indicated 58°. I next turned back the sternum 



* In this connection it should be stated that the Florida Black Bear, Ursus 

 floridanus, continues to hibernate without regard to temperature and at a time when 

 "palmetto berries" (Serenoa serrulata), its favorite food, are abundant. 



