682 ANIMAL HEAT 



fever ' that is to say, a fever due solely to increased metabolism 

 in the nervous system exists; for in a curarized animal a large 

 amount of ' active ' tissue (glands, heart, smooth muscle) still 

 remains in physiological connection with the brain and cord. But, 

 as a matter of fact, in an animal under a dose of curara sufficient 

 to completely paralyze the skeletal muscle cocaine causes no appre- 

 ciable rise of rectal temperature; and this is strongly in favour of 

 the view that the fever produced in the non-curarized animal is 

 connected with excessive muscular metabolism. 



Significance of the Increased Temperature in Fever. It remains 

 to ask whether the rise of temperature is anything more than a 

 superficial and, so to speak, an accidental circumstance. The 

 question has already been raised in discussing the changes in the 

 circulation in fever (p. 680). The orthodox view for many ages 

 has undoubtedly been that the increase of temperature is in itself 

 a serious part of the pathological process, a symptom to be fought 

 with and, if possible, removed. And, indeed, it is not denied by 

 anyone that the excessive rise of temperature seen in some cases of 

 febrile disease (to 43 C., or even to 45) is, apart from all other 

 changes, a most imminent danger to life, unless, as is sometimes the 

 case (in influenza, e.g., where a temperature of 44 has been observed), 

 the high temperature lasts only a short time. Experimental heat 

 paralysis, a condition in which all voluntary and reflex movements 

 are abolished, is produced in frogs by raising the internal tempera- 

 ture to about 34 C. On cooling, the animal recovers. A similar 

 condition can be induced in mammals, but, of course, at a higher 

 temperature. The central nervous system succumbs before the 

 peripheral structures. The superior cervical ganglion in the cat 01 

 rabbit loses the power of transmitting nerve impulses at 50 C 

 But some evidence has been brought forward, mostly from the ficlc 

 of bacteriology, to support the idea that in infective processes the 

 rise of temperature is of the nature of a protective mechanism, that 

 the fever is, indeed, a consuming fire, but a fire that wastes the body, 

 to destroy the bacteria. The streptococcus of erysipelas, for ex- 

 ample, does not develop at 39 to 40 C., and is killed at 39*5 to 

 41 C., and erysipelas infections in rabbits are less virulent if the 

 body-temperature be artificially raised. Anthrax bacilli, kept at 

 42 to 43 C. for some time, are attenuated, and when injected into 

 animals confer immunity to the disease. Heated for several days 

 to 41 to 42 C., pneumococci render rabbits immune to pneumonia, 

 and in rabbits in which ' puncture ' fever has been induced pneumo- 

 coccus infections run a milder course. These bacteriological results 

 are supported to a certain extent by clinical experience. For it has 

 been observed that a cholera patient with distinct fever has a 

 better chance of recovery than a case which shows no fever. But 

 too much weight ought not to be given to isolated facts of this sort, 



