OF ANIMALS. 29 



to be continually purified from all superabundant and extrane- 

 ous substances, by means of secretion. They occur on the ex- 

 ternal and internal surfaces, sometimes through the gaping 

 orifices of vessels opening on large surfaces, which permit the 

 secreted liquid to ooze out; while at others it is from the bot- 

 tom of small cavities formed in the skin or in the mucous 

 membrane, that we perceive this percolation; again, we ob- 

 serve the circulating vessels communicating with proper ves- 

 sels or ramified excretory canals, which are also formed by the 

 envelope of the body, and which pour out the secreted liquid. 

 Among the liquids which are the result of secretions, some 

 are necessary to the exercise of functions, others are entirely 

 rejected as superfluous and extraneous, which constitutes a kind 

 of depuration. The nutritive fluid continually supplied by in- 

 testinal absorption, maintained in a proper state by respira- 

 tion and secretions, is sent into every part of the body, und 

 there effectuates nutrition, a wonderful process in which this 

 fluid is decomposed in such a manner, that in every part of 

 the body a portion of the blood becomes solid, and constitutes 

 an integral part of the organ; when at the same time, and in 

 every part also, a portion of the organs returns to a liquid state, 

 and again enters into the vortex of the circulating fluid. 

 Generation, or the production of a new being, is so diversified 

 in its modes, that it presents no distinctive character peculiar 

 to animals and common to them all. The separation of the 

 sexes, which is subordinate to motion, is in fact, neither peculiar 

 nor common to the animal kingdom. Animals possess also the 

 power of reproducing by a kind of vegetation, certain parts 

 when they are removed, although in a smaller degree than 

 vegetables. 



14. Muscular motion, sensations and nervous action, give 

 to animals, in a manner, a new life. These functions have 

 consequently received the appellation of animal life, in op- 

 position to the other functions called organic or vegetative 

 life. The impressions produced by external agents on the or- 

 gans of sensations, i. e. on the external or internal skin, or in 

 a peculiar manner on some of their organized parts, induce in 

 these organs actions which are transmitted by the nerves to 



