426 NOTES. 



Note 35, pagt, Jll. The high body -temperature of the true warm- 

 blooded creatures, birds and mammals, oscillates within very narrow 

 limits. In man it rises to 36-38 C. ; in dogs to about 30 ; in the sheep 

 to 40 or rather more; in birds it is higher, rarely under 40 and 

 usually as high as 42 to 43 C. (For very ample data see M. Ed. Anatomie 

 ct Physiolcr/ie Corny., viii. pp. 16-18.) In cold-blooded animals even it is 

 always a little higher than that of the surrounding medium, but it 

 rises and falls with this, while the true warm-blooded animals maintain 

 the same, or nearly the same, temperature in spite of the variations in 

 the air or water. How far this may also prove to be the case with 

 such cold-blooded animals as have a temperature considerably higher 

 than that of the surrounding medium has not yet been investigated ; 

 we know, for instance, from Davy, that in Bonitos the temperature 

 is 1 C. above that of the water ; in Pelamys sarda, 5 ; according to 

 Czermak, the Proteus of the Adelsberger grotto has an internal heat 

 of sometimes 5'6 C. above that of the water. It may also be men- 

 tioned that some species of Python, when depositing eggs, have a body- 

 warmth of 6 C., and that sometimes a very considerable degree of heat 

 prevails in a b'eehive. 



Note 36, page 112. The facts given by Horvath are of the greatest 

 interest. The following is perhaps of the highest physiological impor- 

 tance. It is usually supposed that the awakening of winter-sleepers 

 is occasioned by a rising temperature ; but in Horvath 's investigations 

 this was never the case ; during two hours and forty-five minutes, which, 

 in the one experiment communicated, were needed for complete awaken- 

 ing, the temperature of the room remained oxactly the same 10 C. as 

 during the three previous days when the animal was still asleep. This 

 proves that the waking up of the weasel must be caused by some internal 

 cause which we do not as yet know. But his other observation is far 

 more remarkable ; namely, that during the awakening, the body tem- 

 perature of the weasel rises rapidly, and more rapidly during the second 

 half of the process than at the beginning ; for instance, in the experi- 

 ment which is given in detail it rose in the first hour and fifty-five 

 minutes only about 6'6 C., and in the following fifty minutes about 

 17. This remarkably rapid increase of body-heat took place, moreover, 

 without any vigorous movements, which might otherwise have been sup- 

 posed to cause it even the rapidity of breathing showed no increase 

 corresponding to the rise of temperature. 



I must not here pass over in silence the view lately expressed to me 

 by Dr. August Forel, of Munich (well known by his admirable researches 

 on Ants) ; a view founded on certain observations, hitherto unpublished, 

 that winter-sleep does not depend at all on the diminished temperature 

 in winter, but rather on influences determined by food. A dormouse 

 that he kept went to sleep even at a high temperature of the air, in 

 August and September, and slept as soundly as in a true winter-sleep, 



