THE COASTS OF SICILY. 261 



act — viz., digestion, which prepares the food; absorp- 

 tion, Avhich separates the useless parts, isolates the 

 essential principles, and causes them to penetrate 

 into the organism ; circulation, which transports 

 these principles to all the points at which their 

 presence is necessary ; and, finally, respiration, which 

 restores to the nutrient liquids, after they have been 

 changed by their sojourn in the organs, the vivi- 

 fying action by which they are characterised. 



In the superior animals — that is to say, those in 

 which the organisation acts in the highest degree of 

 perfection — each of these functions is accomplished 

 by the aid of special organs. The first naturalists 

 who endeavoured to penetrate into the mysteries of 

 the mechanism of life, directed their studies only to 

 these complicated organisms, and, being forcibly 

 struck by this fact, they declared that the function 

 was at all times and in all cases dependent on the 

 organ. In other words, that where no special in- 

 strument was present for the accomplishment of the 

 function, that function could not exist. However 

 rational this princi[jle may appear to be, it is not the 

 less a profound error ; for w^e find that among the 

 lower grades of the animal scale there are no distinct 

 organs, and yet these animals feed and are nourished 

 — that is to say, they digest, absorb, and respire, and 

 plastic fluids circulate through all their tissues. 



We will take, by way of illustration, one of those 

 fresh-water Hydras so common in the neighbourhood 

 of Paris, which were first recognised by Trembley, 

 and to the study of which M. Laurent * has con- 



* M. Laurent, formerly a Navy surgeon, who died recently 

 s 3 



