jteii INTRODUCTION TO THE 



tice, in his chapter on vefaniae, ( Fir ft 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 necei7ary to 

 the fupport of life, the living Mate of animals does not confifc in that 

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

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

 which the action of the heart itfelf depends," c. Andalfo the re- 

 marks on the effects of ftlmuli 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 inconciuiive and exceptiona- 

 able, in others quite unphilofophical. This enquiry was intended as a 

 counterpart to the experiments of BLAGDEN, arid hig afFociares in the 

 heated 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 exhauftion 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 ye/Tel in which he was to be frozen to 

 death, to the roufing of animal aft ion by cold! He feems to take little 

 notice of the vital organs, the fire-place whence the conltitution 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, frog, eel and fnail, may be as well explained 

 on the idea of the increafed fufceptibility of impreflion, produced by 

 the fubducticn of itimuli, and by an extraordinary exertion of the 

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

 author's hypothecs, which may be fummed up in this general con- 

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

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

 feems to act as ^J^mulant^ exciting the animal powers to exert them- 

 felves for felf-prefervation. 



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

 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 confiderably more 

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

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

 fulated aphorifms, fometimes entirely true, and fome containing only a 

 mixture of truth ; or fiame flrange and whimfical hypothefes, by aid 

 of which, a f > general principles, they attempted to explain things ; 

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

 trace the corporeal functions, by partial induction, to the etfaftSkytv. 



XxQoXlMO Or COMMON SENSORY. 



tSuch was the condition of medical fcience, until almoft twenty-five 



year 

 * Materia Medka, p. 67, c. 



