ECOLOGICAL 6i 



What are the significant facts in regard to the state of the body 

 during hibernation ? One of them, well worked out by Prof, E. W. 

 earlier of Birmingham, is that the constitutional change is very 

 thoroughgoing, like a disease indeed. There are subtle alterations 

 in the inmost recesses of the body, and not all on the minus side, for 

 the irritability of some of the muscles is markedly increased. 

 Another general feature is the all-round reduction of the meta- 

 bolism; the wheels of life are slowed; expenditure is at a minimum; 

 the fire is hardly burning. There is little or no respiration, as is shown 

 by the beautifully exact measurements which Weinland and Riehl 

 and other physiologists have made of the minute output of carbonic 

 acid gas. A correlated fact is the lowering of the temperature 

 towards that of the surroundings, for there is no attempt made to 

 keep up the characteristic mammalian warm-bloodedness. It is 

 not so much, we think, that the heat-regulating arrangements 

 break down, as they do in the opposite extreme of fever; it is rather 

 that they are given up when hibernation is signalled. In any case, 

 the temperature sinks till it may be only i° C. above that outside 

 of the body (as in the spiny ant-eater and some bats). It should be 

 remembered that the temperature of cold-blooded animals is nor- 

 mally just a little above that of their surroundings (i° or so in 

 fishes, 4° or so in amphibians, 4° to 8° in reptiles). Pembrey and 

 Hale found hibernating dormice with a temperature of 9° to 14* 5° C. , 

 instead of a normal of 31° to 36° C, and Mares found bats in a grotto 

 at Maestricht with a temperature of 7° to 7- 2° C, when the external 

 temperature was 6-4° to 7-7° C. It is very interesting to find that 

 many of the hibemators have in the summer a variability of body 

 temperature greater than is usual among mammals. A fourth 

 general feature is of a different order, that the hibernating capacity 

 is associated with a tendency to deposit fat, not only in the usual 

 place beneath the skin, but elsewhere — e.g. on the walls of the chest, 

 even pressing the lungs dorsally, in the arm-pit, and at the loins. 

 It was long since recognised that the so-called "hibernating gland" 

 is no gland at all, but a reserve of fatty tissue traversed by blood- 

 vessels. It is plain that winter sleeping could not have been success- 

 ful had it not been associated with laying up a store of fat, the slow 

 combustion of which ensures the necessary minimum of animal 

 heat. Captive hibemators, which have not been able, for some 

 reason or other, to accumulate fat, will not go to sleep. On the other 

 hand, it has been noticed that super-fatted individuals tend to go 

 to sleep too soon, as readers of the Pickwick Papers will remember. 

 The problem of the origin of hibernation remains obscure, and 

 we have sympathy with Horvath, one of the notable investigators 

 of the subject, who said: "In the first place, it is not sleep, and, in 

 the second place, it has nothing to do with winter." In truth, the 

 hibernating state has very little resemblance to normal sleep, and 



