ANIMAL HEAT $97 



below the normal, but considerably above that of its environ- 

 ment. In this condition it has an imperfect thermotaxis, some- 

 thing like that of an ordinary mammal (including the human 

 infant) in the period of immaturity, immediately after birth. 

 When the hibernating mammal awakes the rise of temperature 

 is enormous and abrupt. The temperature of a dormouse rose 

 in an hour from 13-5 C. to 357 C., and that of a bat in fifteen 

 minutes from 17 C. to 34 C. (Pembrey). 



Fever is a pathological process generally caused by the 

 poisonous products of bacteria, and characterized by a rise of 

 temperature above the limit of the daily variation (p. 605). 

 It is further associated with an increase in the rate of the heart 

 and the respiratory movements, and a diminution in the alkalies 

 and carbon dioxide of the blood. The total excretion of nitrogen 

 is increased, at least in proportion to the amount of protein 

 ingested, indicating an increase in the consumption of tissue- 

 protein. The distribution of the nitrogen among the urinary 

 constituents is altered. The ammonia (in the form of ammonium 

 salts of organic acids), the uric acid, and to a smaller extent 

 the kreatinin (Leathes), are increased, while the urea is relatively 

 decreased, even when its absolute amount is greater than normal. 

 Kreatin, which is not normally present in urine, unless the food 

 contains it, may also appear in fever (Shaffer). It has been 

 suggested that the proximate cause of fever is the action of 

 bacterial poisons or of other substances on the ' heat centres/ 

 and that antipyretics, or drugs which reduce the temperature 

 in fever, do so by restoring the centres to their normal state, by 

 preventing the development of the poisons, aiding their elimina- 

 tion, or antagonizing their action. In favour of this view, it 

 has been stated that when the basal ganglia are cut off, by 

 section of the pons, from their lower nervous connections, fever 

 is no longer produced by injection of cultures of bacteria which 

 readily cause it in an intact animal, while antipyrin has no 

 influence upon the temperature (Sawadowski) . But some 

 observers have been unable to find any clear evidence of the 

 existence of ' heat centres ' that is, of localized portions of 

 the central nervous system specially concerned in the regulation 

 of the body-temperature. And while it is almost certain that 

 some pyrogenic or fever-producing agents cocaine, e.g. act 

 indirectly, through the brain or cord, it is quite possible that 

 others affect directly the activity of the tissues in general, just 

 as some antipyretics or fever-reducing agents, such as quinine, 

 act immediately upon the heat-forming tissues, so as to diminish 

 their metabolism, while others, like antipyrin, affect them 

 through the nervous system. Quinine has no influence upon 

 ' puncture ' fever in rabbits. A still more important action of 



