50 HORSE-BACK RIDING. 



peculiarity which predisposes to haematosis, is, accord- 

 ing to Woillez, to be attributed rather to the action 

 of the general muscular system than to the muscles 

 of the thorax or those of the upper portions of the 

 body. 



And, lastly, there is a phenomenon which cannot 

 justly be separated from respiration ; it is the cuta- 

 neous exhalation, which is sensibly affected by 

 horse-back riding. In fact, the increase of the sur- 

 face circulation, by bringing to it a greater quantity 

 of blood, favors cutaneous respiration. The evapora- 

 tion of the vapor of water and the exhalation of 

 carbonic acid are increased, and more oxygen is ab- 

 sorbed by the skin. As we have already remarked 

 concerning the circulation, respiration becomes grad- 

 ually normal with repose. 



4. Nervous influence. — If ever a subject has been 

 much discussed, much experimented and written 

 upon, it is certainly that which treats of nervous 

 action. What is its nature, its function, and how 

 does it act ? These are the questions we are 

 still led to ask, for if light has been thrown upon 

 some points, there are others which still remain in 

 darkness. 



Physiology shows us the arterial blood penetrating 

 the organs, and there undergoing a transformation 

 into venous blood, and by this change performing a 

 work in relation with the parts to w^hich it penetrates. 

 We have shown that the chemical action produces the 



