282 Dr Alison on the Principle of Vital Affinity . 



of Mr Goodsir, is provided.* And this also enables us to 

 understand a general fact, which, although disputed, I be- 

 lieve to be both true and important in pathology, — that a 

 substance destined for excretion, but retained in the blood by 

 reason of disease of its excreting gland (particularly the bile 

 or urine), is more injurious than the same matter when se- 

 creted by the gland, but re-absorbed from a mucous surface, 

 and consequently subjected to cellular action, and thereby to 

 chemical change. 



III. Another general fact appears to be sufficiently illus- 

 trated by observations on the chemical changes in living bodies, 

 — viz.. That the vital properties by which these are effected 

 are trans/erred from the portions of matter already possess- 

 ing them, to those other portions of matter which are either 

 taken into their substance, or deposited in their immediate 

 neighbourhood. It is, indeed, obvious, that if we are right 

 in saying that living matter possesses these peculiar vital 

 properties, the act of assimilation which we know to be con- 

 tinually going on in living bodies, is not merely the attraction 

 and addition of new matter, but must include this transference 

 of vital properties to the matter which is continually added 

 to the existing solids. 



" The force with which life is kept up," says Professor 

 Whewell, " not only produces motion and chemical change, 

 but also vitalizes the matter on which it acts, giving it the 

 powder of producing the same changes in other matter, and 

 so on indehnitely. It not only circulates the particles of 

 matter, but puts them in a stream, of which the flow is de- 

 velopment as well as movement." — {Philosophy of Inductive 

 Sciences^ vol. ii., p. 52.) 



Several facts which are known in physiology and patho- 

 logy, may be noticed as more special exemplifications of this 

 principle. Thus, we know that vessels in any part of the 

 body communicate certain properties to the whole mass of 

 blood which lies in contact with them, so as to modify or sus- 

 pend for a long time the coagulation of such blood ; — that W\q 



* See Carpenter's Manual of Physiology, § 493. 



