THE BIOLOGICAL SCIENCES AND MEDICINE. 805 



that oue half of a modern text-book of physiology consists of applied 

 physics and chemistry ; and that it is exactly in the exploration of the 

 phenomena of sensibility and contractility that physics and chemistry 

 have exerted the most potent influence. 



Nevertheless, Bichat rendered a solid service to physiological prog- 

 ress by insisting upon the fact that what we call life, in one of the 

 higher animals, is not an indivisible unitary archaeus dominating, from 

 its central seat, the parts of the organism, but a compound result of 

 the synthesis of the separate lives of those parts. 



" All animals," says he, " are assemblages of different organs, each 

 of which performs its function and concurs, after its fashion, in the 

 preservation of the whole. They are so many special machines in the 

 general machine which constitutes the individual. But each of these 

 special machines is itself compounded of many tissues of very different 

 natures, which in truth constitute the elements of those organs " {loc. 

 cit., Ixxix). " The conception of a proper vitality is applicable only 

 to these simple tissues, and not to the organs themselves " {loc. cit., 

 Ixxxiv). 



And Bichat proceeds to make the obvious application of this doc- 

 trine of synthetic life, if I may so call it, to pathology. Since diseases 

 are only alterations of vital properties, and the properties of each tis- 

 sue are distinct from those of the rest,' it is evident that the diseases of 

 each tissue must be different from those of the rest. Therefore, in 

 any organ composed of different tissues, one may be diseased and the 

 other remain healthy ; and this is what happens in most cases {loc. cit., 

 Ixxxv). 



In a spirit of true prophecy, Bichat says, " We have arrived at an 

 epoch, in which pathological anatomy should start afresh." For as 

 the analysis of the organs had led him to the tissues, as the physio- 

 logical units of the organism ; so, in a succeeding generation, the anal- 

 ysis of the tissues led to the cell as the physiological element of the 

 tissues. The contemporaneous study of development brought out the 

 same result, and the zoologists and botanists exploring the simplest 

 and the lowest forms of animated beings confirmed the great induction 

 of the cell theory. Thus the apparently opposed views, which have 

 been battling with one another ever since the middle of the last cen- 

 tury, have proved to be each half the truth. 



The proposition of Descartes that the body of a living man is a 

 machine, the actions of which are explicable by the known laws of 

 matter and motion, is unquestionably largely true. But it is also true 

 that the living body is a synthesis of innumerable physiological ele- 

 ments, each of which may nearly be described, in Wolff's words, as a 

 fluid possessed of a " vis essentialis," and a " solidescibilitas " ; or, in 

 modern phrase, as protoplasm susceptible of structural metamorphosis 

 and functional metabolism ; and that the only machinery, in the pre- 

 cise sense in which the Cartesian school understood mechanism, is that 



