AND ANIMAL LIFE. 169 



the office of both is to maintain as exact as possible 

 the balance between the powers which add and 

 those which subtract. From the weak propelling 

 force of the heart, and the agency of the exter- 

 nal cold, the energy of circulation and the quan- 

 tity of blood will necessarily diminish, as we re- 

 cede from the heart to the surface of the body. 

 If the wants of the system were not regulated 

 according to these conditions, the function of 

 respiration and the motion of the heart would be 

 inadequate to preserve in existence the collective 

 instruments of life. By circumscribing the extent 

 of circulation by means of ligatures, as was prov- 

 ed by LEGALLOIS, or by lessening the demands 

 of the constitution, as in torpidity, by the suc- 

 cessive reduction of the energy of circulation, and 

 the quantity of blood from the heart to the sur- 

 face of the body, we enable the heart to contract, 

 and the lungs to improve the qualities of the san- 

 guineous fluid. The experiments of LEGALLOIS 

 demonstrate the correctness of what is advanced. 

 " Si avant de detruire la moelle on fait des liga- 

 tures, soit a Paorte, soit a quelques gros troncs 

 arteriels, les resultats sont diflerens, et la des- 

 truction de la meme portion de moelle, qui, sans 

 ces ligatures, eut arrete subitement la circula- 

 tion, sera insuffisante pour produire cet effet. 

 En general, en resserant par des ligatures Teten- 

 due des parties auxquelles le cceur doit distribuer 

 le sang, on diminue la somme des forces dont cet 

 organe a bcsoin pour remplir sa function, et Ton 



