Theories and Experiments 287 



And so, according to M. Lortet and M. Marcet, who expresses 

 himself even more definitely than his travelling companion, there 

 is a considerable drop in body temperature, and this drop is due 

 "not to an effect of the rarified air", but to the muscular move- 

 ment, to the transformation of heat into work. 



But these physiologists found in M. Forel an adversary worthy 

 of them. 



The excellent work of the professor of Lausanne is divided into 

 three parts published, one in 1871, the last two in 1874. It was 

 undertaken first as a criticism of the memoirs of MM. Marcet and 

 Lortet. M. Forel 125 begins with very just criticisms of the use of 

 the buccal thermometer, as an indicator of the real temperature 

 of the body. I copy here his observations, to the complete accuracy 

 of which I can testify in many circumstances: 



First, it is very difficult to keep the lips hermetically closed for a 

 sufficient time, and only after a rather large number of attempts and 

 experiments could I become completely enough accustomed to it so 

 that I could be sure that not even one bubble of air was admitted 

 during the experiment. What is difficult in a state of repose becomes 

 unendurable while one is climbing, when one begins to pant, when all 

 the openings together are not enough to admit a sufficient quantity of 

 air into our lungs, especially when the rarefaction of the air demands 

 imperiously a larger volume than we need on the plain so that our 

 system may be supplied with enough oxygen; then it is regular torture 

 to close for ten minutes the mouths which we should like to be able 

 to enlarge, and the experiment becomes terribly painful. 



Another difficulty is to keep the thermometer exactly under the 

 tongue, and as much as possible always in the same place. The tongue 

 is very flexible and fairly docile; it can, if need be, surround the bulb 

 of the thermometer closely enough not to permit contact with the air 

 of the mouth; but the thing is very difficult, as one can convince him- 

 self before a mirror, and what is difficult when one is at rest becomes 

 almost impossible under the painful conditions of the experiment. 



Now if any portion of the surface of the bulb is in contact with 

 the air of the mouth, the results are greatly modified. In fact, the 

 buccal cavity is not closed at the back, the opening of the palate per- 

 mits a constant mixture of the air contained in the mouth and the air 

 which circulates with violent impetuosity in the canal of the pharynx; 

 even if there is no current of air in the buccal cavity properly so- 

 called, this mixing necessarily takes place, and in proportions which 

 are greater, as the current of air in the pharynx is more violent and 

 the differences of temperature and humidity between the pharyngeal 

 air and the buccal air are greater. In our conditions of experimenta- 

 tion on lofty mountains we are as unfavorably placed as possible from 

 this point of view. The respiration is panting in a very dry and very 

 cold air. The mixing of air must necessarily increase in amount with 

 the altitude and with the muscular movements which accelerate the 

 respiration. 



