A STUDY OP FEVER. 33 



motor impulses — but it may be tlieir function to receive the 

 impulse from above as their normal stimulant, which shall ex- 

 cite them to send an impulse, which is received, not by the vaso- 

 motor muscle fibres, but by cells of the so-called sympathetic 

 ganglia. The anatomy of the nervous sj^stem appears to me to 

 point to this method of action, but a still stronger indication 

 of it is afforded by the experiments of Schlesinger (Wiener 

 Med. Jahrb. 1874), who found, in agreement with other ob- 

 servers, that when the cord is cut in the dog irritation of a 

 sensitive nerve has no effect upon the arterial joressure, but 

 who also discovered that if the animal were poisoned with 

 strychnia, irritation of a sensitive nerve did induce rise of the 

 arterial pressure. 



If there be no fallacy underlying these experiments, it would 

 appear a rational explanation of these results that strychnia so 

 excites the nerve cells of the spinal cord as to cause them to 

 respond to an impulse from below, which, under ordinary cir- 

 cumstances, is unable to affect them. Be these things, however, 

 as they may, the cardinal fact seems absolutely proven by the 

 concurrent experiments of five observers that the chief or 

 governing vaso-motor centre is in the medulla oblongata. 



From the facts and arguments which have been adduced, it 

 is very certain that the rise of temperature which follows sepa- 

 ration of the pons and the medulla is not due to an}- disturb- 

 ances of circulation, the vaso-motor centres not being implicated 

 by the o}3eration. Moreover, as already stated, in my experi- 

 ments the rise occurred in dogs in which the bloodvessels were 

 almost empty, as well as when the arterial pressure was rather 

 above normal. 



Can the rise be due to changes in the respiration ? Certainly'' 

 not. In the first it is not conceivable that anj^ departure from 

 normal respiration should have the power to induce such rapid 

 3 



