repout on animal physiology. 105 



In this way Haller restricted the vital powers to two, — sensi- 

 bility and irritability ; the one exhibited in the brain and nerves, 

 the other in muscular fibre. His doctrine was vehemently op- 

 posed by Whytt, De Haen, Verschuir; and strenuously de- 

 fended by himself, by Bonnet, and by Fontana. It was seen that 

 many parts in the animal body to which neither irritability nor 

 sensibility, in Haller's sense, could be extended, were not the 

 less alive. Thus during the numerous controversies which arose, 

 errors on each side were detected ; materials for more extended 

 views were accumulated ; experiments were infinitely multiplied 

 and eagerly criticised ; the excitability of various tissues, to which 

 Haller had denied that quality, because he had not called it into 

 action by an appropriate stimulus, was established on the one 

 hand, and on the other the mistake of confounding nervous in- 

 fluence with sensibility was made apparent. Thus the more pro- 

 bable it became that irritability and innervation are separate 

 powers, so did it follow the more necessarily that every different 

 part should have its own excitability and its own degree of ner- 

 vous power, and hence its own peculiar mode of life, — an opi- 

 nion announced by Bordeu, Barthez, Blumenbach *. Indepen- 

 dently of these expressions of vital energy in the various tissues, 

 these physiologists admitted a fundamental power, which they 

 termed vitality, or vis viice, of which the different degrees of 

 excitability and sensibility were considered merely as modes, 

 according to the organs in which the vital energy operated. But 

 the analogies thus assumed between the ph«enomena were not 

 established by any proof; the modifications of the original power 

 were not accounted for ; and this theory, apparently philosophic, 

 has no firm foundation when its partisans would represent vitality, 

 or oxygen, or galvanism, as a proximate cause of all the phaeno- 

 mena, residing in living matter as gravity does in deadf. 



It might have been foreseen that this analytical mode of treat- 

 ing the living organism, — this isolation of powers which had 



• They liad all been anticipated by F. Glisson, who was President of the 

 College of Physicians in 1677; but the opinions of a man who was a century in 

 advance of the age in which he lived, and which were obscured by metaphysical 

 subtleties and scholastic language, had no great influence, upon those who were 

 engaged with mathematical or chemical theories of life. He proved the exist- 

 ence of a peculiar quality of living bodies, which he first named Irritability; 

 distinguished between perception and sensation, and adduced as instances of 

 perception without sensation, the contraction under stimulation of the heart and 

 muscles when separated from the body ; insisted that it was only through this 

 natural perception and sensation, and not immediately, that the animal appetite 

 on the one hand, and the mind on the other, puts the innate irritability in action, 

 and so produces all motions, which are either natural and vital, or sensitive. 



t Thompson's Life of Ciillen. 



