508 Medicine. [Chap. IV^ 



denominates irritability, has been since proved by 

 ii great variety of facts to be susceptible of two re- 

 markable changes in the living fibre, viz. increase 

 and diminution, depending upon the abstraction 

 or accumulation of stimulant powers. In support 

 of this general principle, which is supposed univer- 

 sally to belong to animated nature, the aid of many 

 facts, derived from the vegetable kingdom, has beeii 

 recently added. As the functions of the animal 

 economj', viz. sensation and voluntary motion, to 

 which I lie nerves seem alone to be necessary, are* 

 never satisfactorily observed in the vegetable king- 

 dom, it is presumed that the absence of nerves in this 

 kingdom can in no degree diminish the analogy 

 which is attempted to be established between these 

 two grand divisions of created nature. It is con- 

 tended by these physiologists, that there is a prin- 

 ciple of action common to both kingdoms, upon 

 which their respective functions chietly depend, and 

 which is believed to be governed by the same laws 

 as are laid down for the regulation of the irritability 

 of the animal fibre. By the term irritability, nothing 

 more is here meant than merely to express -a act ; 

 which fact is this, that certain parts of animals and 

 vegetables are possessed of a propertv', by which, 

 upon the application of a stimulus, the ends of a 

 straio-ht fibre approach nearer to each other, and 

 the diameter or area of a curved or circular one is 

 diniini.siicd. 



For the facts respecting the functions of vegeta- 

 bles from which tiie above-mentioned principles 

 have been drawn, the world is indebted, among 

 many others, to Males, Grew, Duhamel, Bonnet, 

 J^ufton, Spallanzaui, des Fontaines, Gmelin, Ingen- 



