OF ANIMALS. 39 



the most general of these organs, does not yet exist in the 

 arachnidestracheariae, but under the form of a separated vessel 

 as in insects; on the contrary, in the arachnides pulmonariae, 

 and in the Crustacea, we still find the liver divided into dis- 

 tinct lobes, or as in some, in the form of a hunch of grapes. 

 The mollusca have a very considerable liver; most of them 

 have salivary glands, but neither pancreas nor kidneys. Se- 

 veral have secretions peculiar to themselves. All the verte- 

 brated animals have glands, and in addition to what the others 

 possess, they have kidneys, organs which have many points 

 of relation with those of generation. Among the liquids 

 which result from the various secretions, some have their ap- 

 propriate use in the exercise of the functions, as saliva, bile, 

 &c.; others, such especially as the urine are rejected as su- 

 perfluous and hurtful. 



Thus the organs of the nutritive functions in their great di- 

 versity, consist in a permeable absorbing substance, which as- 

 similates and excretes; in one or two surfaces, the skin and 

 intestines, which foreign substances have to traverse from 

 without inwardly, or from within outwardly by absorption, 

 or by excretion; in vessels which establish communications 

 between the surfaces of the body and all the parts of its sub- 

 stance, and vice versa; in respiratory organs, which are a por- 

 tion of the surfaces, where the liquid comes in contact with 

 the atmosphere, and in secretory organs, another part of the 

 surfaces, where a portion of the liquid is rejected. 



23. Generation, or the production of a new being simi- 

 lar to the one to which it owes its origin, is the second func- 

 tion in point of importance, common to all organized and liv- 

 ing bodies, and presents also in animals a great variety in its 

 organs and phenomena. This function in its simplest state, 

 has no particular organ ; but the whole body being very sim- 

 ple and homogeneous, divides itself in several fragments, 

 each of which preserve the properties of the whole mass; 

 this is called the fissiparous generation, it belongs especially 

 to the infusorii, and exists accidentally in others. In some 

 animals of the same class, we observe in the substance of the 

 body globules or corpuscular substances which appear capa- 



