340 THE BIOLOGICAL SCIENCES AND MEDICINE. [LECT. 



the work of Caspar F. Wolff, 1 by demonstrating the 

 fact that the growth and development of both plants 

 and animals take place antecedently to the existence 

 of their grosser organs, and are, in fact, the causes 

 and not the consequences of organisation (as then 

 understood), sapped the foundations of the Cartesian 

 physiology as a complete expression of vital pheno- 

 mena. 



For Wolff, the physical basis of life is a fluid, 

 possessed of a " vis essentialis " and a " solidescibili- 

 tas," in virtue of which it gives rise to organisation ; 

 and, as he points out, this conclusion strikes at the 

 root of the whole iatro-mechanical system. 



In this country, the great authority of John 

 Hunter exerted a similar influence ; though it must 

 be admitted that the too sibylline utterances which 

 are the outcome of Hunter's struggles to define his 

 conceptions are often susceptible of more than one 

 interpretation. Nevertheless, on some points Hunter 

 is clear enough. For example, he is of opinion that 

 " Spirit is only a property of matter" (" Introduction 

 to Natural History," p. 6), he is prepared to renounce 

 animism (I.e. p. 8), and his conception of life is so 

 completely physical that he thinks of it as something 

 which can exist in a state of combination in the food. 

 " The aliment we take in has in it, in a fixed state, 

 the real life ; and this does not become active until it 

 has got into the lungs ; for there it is freed from its 

 prison" ("Observations on Physiology," p. 113). 

 He also thinks that "It is more in accord with the 



1 "Theoria Generationis," 1759. 



