BIOLOGY. 287 



nothing himself. Nor was it owing to any effect produced upon 

 the circulation by modification of the action of the heart, for in 

 this case other portions of the body would have been influenced 

 likewise, whereas it was found that the head alone was affected, 

 other parts situated full as favorably, if not more so, for feeling 

 any such influence, exhibiting little or no change of temperature. 

 Whatever the cause was, it certainly appeared to have its seat in 

 the head. In all these experiments, changes of position, or any 

 other disturbing cause, were carefully avoided. 



Pursuing these experiments farther, it was found that anything 

 that aroused the attention was capable of causing a greater or less 

 rise of temperature on the part of the head, over and above that 

 of the rest of the body. Various sights and sounds had this 

 effect ; and, indeed, it could be produced in a great variety of 

 •ways. 



In the next place, the effect of the exercise of the higher reason- 

 ing powers was investigated. The results of these experiments 

 were as follows : — 



1. Mental action of this sort caused a rise of temperature 

 on the part of the head, which varied very much in different 

 cases ; the highest rise noticed did not exceed the twentieth of a 

 degree. 



2. The temperature of the extremities fell, sometimes only 

 slightly, but at other times very decidedly, — a half or a quarter 

 of a degree of Centigrade, for example. This fall was doubt- 

 less owing, in part, to the absence of muscular exertion con- 

 sequent upon sitting still, but not entirely so, for mere immobil- 

 ity, without mental exertion, did not produce an equally great 

 effect. 



The most striking effects of all were produced by the reading 

 aloud, or the recitation of poetry. The rise of temperature in 

 this case was not due in any appreciable degree to the muscular 

 exertion involved, for mere mechanical recitation produced no 

 effect ; but the moment the interest of the speaker began to be 

 awakened the temperature rose. 



Although the action of the heart was frequently more or less 

 modified, yet this could not account for the rise of temperature, 

 Inasmuch as other parts of the body ought, in such a case, to have 

 shared equally in the rise, whereas it was the head that was 

 chiefly, if not solely, affected. Reading or reciting to one's self 

 gave similar results, and often even in a more marked degree. 



The success of these experiments must depend, in a great meas- 

 ure, upon individual peculiarity ; and with many persons they 

 would doubtless fail. Beat emotion must be awakened to produce 

 the rise of temperature. Where this condition of the mind ex- 

 isted, out of more than a hundred observations I have never known 

 a failure. 



The rise of temperature in this series of experiments was the 

 highest noticed in all the observations given in this article ; a few 

 mmutes' recitation producing a greater effect than several hours 

 of deep thought. 



In conclusion, I would say that, as regards the particular re- 



