INTRODUCTION. XXI 



transmit at each contraction two ounces, and to 

 contract 75 times per minute, we shall find that 

 the whole mass of blood will pass through the 

 lungs once every three minutes, or twenty times 

 per hour. As it has been proved by direct expe- 

 riment that the blood acquires at least one de- 

 gree of heat in passing through the lungs, it 

 necessarily follows, at this moderate calculation, 

 that the system will receive 20 degrees of heat in 

 an hour, or 240 degrees every twelve hours. If the 

 respiration be accelerated, and the contractions 

 of the heart be increased to 100, the mass of the 

 blood will circulate through the thoracic organs 

 in one-fourth less time than is stated above, and 

 consequently the temperature will be augmented 

 one- fourth : the increase of one degree, instead of 

 being repeated every three minutes, will be re- 

 peated every %\ minutes. 



According to the doctrine of CRAWFORD, 

 the evolution of heat is confined to the ca- 

 pillaries distributed throughout the body ; but 

 the present explanation of the manner in which 

 the system acquires 20 degrees per hour, or 

 240 every twelve hours, is unfavourable to such 

 an opinion, as it proves that the lungs transmit an 



