()g I i: V i: It 



chanfjrs in the gimt il mii liil |in-<viiri , is cnnoboraUtl by tlic nsulls of irritation 

 of a jMTipluTal iht\ 



lu 1870, I*. Ili'idi-iiliain aiinouiicrd {jylihjer'a Archir, y. 504) that when a sensi- 

 tive nrrvc is stiniulatoil, a fall of trnipi-raturc occurs siniultam-oiisly with the rise 

 of thi" blood pressure. I shall not attempt to follow this memoir closely, l)ut shall 

 simply state the results of experiments, the conclusions drawn, and the evidt iit 

 reasons there are for not nllowinj? the justice of the deductions made. 



The experimental facts which were reached are as follows: — 



1st. Irritation of a sensitive nerve causes a rise in blood pressure but a fall in 

 temperature. 



'.M. This fall occurs in the posterior part of tlie Imdy even after the circulation 

 has been cut off by forcible compression of the aorta. 



Ud. When, in animals which have been thrown into a hifjh fever by tlie injection 

 of putriil matters, u .sensitive nerve is stimulated, a rise of blood pressure occurs 

 as in the normal condition, but no vhanye <>/ ti uijitrntiire. 



])r. Ileidenhain Ulieves that wlien the blood pressure rises the blood current 

 moves more rapidly, and that tiie fall of temperature is due to the surface blood 

 being returned more quickly to the internal organs and thereby cooling them more 

 rapi<lly than normal. It seems scarcely necessary to point out that if the blood is 

 returned more rapidly to the interior, it of necessity remains upon the ext(>rior for 

 a shorter period, and is cooled less than normal. It makes no difference whether 

 a (juart of fluid cooled one-tenth of a degree, or a pint cooled two-tenths of a degree 

 is returned in a given time, so far as tlie general temperature is concerned. More- 

 over it has been distinctly proven in an earlier part of this memoir, fliat vaso- 

 motor paralysis, not spasm, favors rapid dissipation of heat. Either the second 

 or the third of Ileidenhain's asserted experimental facts seems, to my mind, 

 entirely sufficient to prove the incorrectness of his theory; for if the fall of 

 temperature occurs in a part which is deprived of its blood, or if it does not occur 

 in fever although the nerve irritation has its usual effect upon the blood ])n'ssure, 

 how can alterations in thi- l)lood pressure be the cause of the fall ! The improbability 

 of Ileidenhain's theory is further shown by the circumstance that in some of his 

 experiments the temperature fell steadily after galvanization of a nerve though the 

 animals were wrapped in wool. (^n the whole, the proof appears to be very 

 strong that the fall of temperature which follows galvanization of a sensitive nerve 

 is not due to an increased dissipation of heat from the body owing to changes ia 

 the circulation. 



The work of Ileidenhain lias been reviewed and extended by Dr. 1". Iliegcl 

 (Pjlit'jrr'n Arr/i!v, 1S71, IJd. iv.), who found that the fall of temperature ditl not 

 always occur when tlie nerve was irritated, although the blood pressure always rose, 

 and also that the temperature usually remained at the minimum point for a long 

 time after the witlidrawal of the stimulus, although the blood i)ressure returned 

 at once to the normal point. 



The «-xperiments and r<-sults n( liei.b-iiliain were, imleetl, not entin ly novel. 

 The same ground appears to h.i\e bi-en covcn-d by Mantigazza. "Where bis memoir 



