

INTRODUCTION TO THE 



ticc, in his chapter on vefanias, (Firfl Lines, § 1544. and feq.) as 

 well as the obfervations in his letter on the recovery of perfons drown- 

 ed : (p. 4.) " Though the circulation of the blood is neceffary to 

 the fupport of life, the living (late of animals does not confift in that 

 alone, but efpecially depends upon a certain condition of the nerves 

 and mufcular fibres, by which they are fenlible and irritable, and upon 

 which the action of the heart itfeif depends," &c. And alfo the re- 

 marks on the effect of ftirnuli in keeping up the action and energy of 

 the brain* at all times, in his treatife upon the materia medica. 



John Hunter had been fpeculating too on this fubject. In his 

 experiments on animals, with refpect to their power of producing 

 heat, he has brought curious and important facts to view : though 

 his reafoning on them is in fome inftances inconclufive and exceptiona- 

 ble, in others quite unplulofophical. This enquiry was intended as a 

 counterpart to the experiments of Blagden, and his affociates in the 

 heaied chamber, on the power of the human body to produce cold in 

 high temperatures. He afcribes a great deal, throughout his per- 

 formance, to the ftimulant action of cold, and to the exhauflion of 

 the whole of the powers of life in freezing animals, by their efforts to 

 produce heat ; he even afcribes the attempt of his poor victim, the 

 dormoufe, to get out of the veffel in which he was to be frozen to 

 death, to the roufing of animal aBion by cold 1 He feems to take little 

 notice of the vital organs, the fire-place whence the constitution re- 

 ceives its warmth ; nor regard much the condition of the refpiratory 

 function in any of the creatures he operated upon, nor the pain they 

 endured, and the changes in their economy confequent upon it. The 

 experiments on the egg y frog, eel and fnail, may be as well explained 

 on the idea of the increafed fnfceptibility of imprefiion, produced by 

 the fubduction of ftirnuli, and by an extraordinary exertion of the 

 refpiratory organs caufing a greater evolution of heat, as upon the 

 author's hypothefis, which may be fummoned up in this general con- 

 clufion ; that cold produces its effect in fufpending the voluntary ac- 

 tions, by acting as a fedative to a certain point ; beyond which it 

 feems to act as a. Jli mutant, exciting the animal powers to exert them- 

 felves for felf-prelervation. 



It will be evident to him who reflects on what has been related, 1 

 that the Epicurean Sectaries entertained no other than mechanical 

 notions concerning the production, actions, and changes of bodies ; 

 and that Hippocrates and his followers, though coniiderably more 

 advanced towards the truth, had gone no farther than to obferve foli- 

 tary and individual facts, arrange thefe into detached fentences, or in- 

 flated aphoriftns, fomctimes intirely true, and fome containing only a 

 mixture of truth ; or frame (trange and whimiical hypothefes, by aid 

 of which, as general principles, they attempted to explain things ; 

 and the molt forward of them feems to have done little more than 

 trace the corporeal functions, by partial induction, to the oct<?3v)}-/>eiov 

 raPohix-vo or common sensory. 



Such was the condition of medical fcience, until almofl twenty-five 



years 



* Materia Medic?, p. 6", &c. 



