80 INSENSIBLE PERSPIRATION. [BOOK I. 



enough for our purpose, that abundantly per- 

 spirable matter lies in and upon the intestines ; as 

 any affection of the heart, arising from the organs 

 of sense {sect. 30.), causes a sudden effusion of 

 blood in the skin, and induces heat and irritation 

 there. Fear, for instance, of the dealer's whip 

 often occasions the skin to contract and expand, so 

 as to cause the tail to shake with every alternate 

 vibration of the heart. In like manner do the in- 

 testines send forth their watery particles, upon the 

 slightest occasion, to the same place of exit, in order 

 to moisten and render it more supple. Whether 

 the very transparent membrane, called peritoneum, 

 which sustains the bowels, or that other large part 

 of it which covers these and all parts of the inside, 

 is most concerned in this secretion and effusion, 

 is not worth the trouble of inquiry here. But in 

 addition to what is said in the last section respect- 

 ing the colour of the lacteal duct, as it passes along 

 the mesentery in case of hide-hound, we may be 

 allowed to observe, that we may daily prove that the 

 sensible perspiration from young and healthy horses 

 contains more of water than is found in feverish, 

 old, or generally unhealthy animals; and that, 

 with these the sweat is more frothy, or becomes so 

 much sooner, the mouth getting clammy, and the 

 tongue dry and hot underneath, with less work than 

 younger ones ; and that horses so affected are always 

 found insatiably craving after water to supply the 

 waste that is constantly going on. Moreover, as 

 regards the connection that subsists between one 



