ANIMAL. 



absorption alone. The mouth is a cavity of 

 extremely varied character and construction 

 adapted universally to the circumstances in 

 which animals exist. Nothing analogous to a 

 mouth is met with in any vegetable. 



The food having been selected and seized is 

 next transferred to the cavity in which it un- 

 dergoes an elaboration that fits it to be received 

 into the proper system of the animal and con- 

 verted into its own substance. We do not 

 find anything like the pouch denominated a 

 stomach in any member of the vegetable king- 

 dom. The matter fitted for its nourishment, 

 absorbed by the root, is transmitted to the 

 stem, and from thence makes its way into the 

 leaves of the vegetable. It does not pass un- 

 changed, however, from the earth into the root, 

 or at least it has advanced but a very short way 

 on its course to the leaves, before it is found 

 to have undergone certain changes, which are 

 also known to be greater in amount as* it is 

 examined at a greater height or distance from 

 the root. Although growing from the same 

 soil too, the sap of vegetables, i. e. the fluid 

 which is passing upwards through the woody 

 fibres, is found to be universally different. 

 Whether the peculiar qualities thus acquired 

 by the simple moisture holding certain salts, 

 &c. in solution, which is the food all vege- 

 tables derive through their roots, be the effect 

 of vital elaboration within the cells of the 

 woody fibre, or result from an admixture of the 

 cambium or fluid which has already undergone 

 assimilation in the leaves, is still uncertain. 

 We are inclined to believe that a process ana- 

 logous to digestion does actually take place 

 within the woody conduits of the sap of vege- 

 tables ; why should it not, or why should 

 any new properties acquired by matters sub- 

 jected to the influence of the peculiar laws 

 of vitality be held as resulting from mere ad- 

 mixture ? 



The very same thing, in fact, happens among 

 the lowest tribes of animals which takes place 

 in all vegetables : the substances fitted for their 

 nourishment penetrate or are absorbed into 

 their systems, and are there assimilated without 

 the intermedium of any special apparatus. 

 We mount but a very short way in the scale 

 of the animal creation, however, before we 

 meet with a peculiar pouch, destined for the 

 reception of the aliment, and accomplishment 

 of the first steps in the processes by which, in 

 the more perfect animals, it is finally assimi- 

 lated. This pouch is the stomach, and with 

 the rest of the digestive apparatus with which 

 it is connected, is in intimate and uniform re- 

 lationship with the kind of food upon which 

 animals are led by their instincts to live. 



All the accessaries of the assimilating cavity 

 or stomach which we find in animals, from 

 the organs of sense that guide them in their 

 choice 'of aliment, to the lips that seize it, the 

 teeth or jaws that bruise it or destroy its 

 vitality, the muscular actions by which it is 

 swallowed, and the chemico-vital processes by 

 which it is dissolved, and the purely vital sen- 

 sibilities by which such parts as are proper for 

 "nourishment are retained, and such as are im- 



proper for this purpose are expelled, all of 

 these are wanting among vegetables. 



There are yet other processes which form an 

 essential item in the acts by which organized 

 beings universally continue their existence, 

 which it is necessary we should include in this 

 summary of the common, particular, and dis- 

 tinguishing attributes of vegetables and ani- 

 mals. One of the most important of these is 



Respiration. The leaves in the more per- 

 fect vegetables are the instruments of respi- 

 ration ; their place is supplied by the general 

 surface in those plants that are aphyllous. Vege- 

 tables that live in air act immediately by 

 means of their respiratory organs upon the 

 ambient medium ; those that live in water, 

 upon the air held in solution by the fluid 

 around them. 



Vegetables are well known to exhale .abun- 

 dantly from the surface of their leaves, or 

 stems, in case they have no leaves. The mat- 

 ter exhaled is principally water. They have 

 also the farther property of decomposing one 

 of the elements of atmospheric air, namely, 

 carbonic acid gas. In the sunshine the leaves 

 of vegetables fix the carbon which enters into 

 the composition of this gas, and set the oxy- 

 gen at liberty ; in the dark, however, a very 

 different process goes forward ; they then 

 actually absorb oxygen and exhale carbonic 

 acid gas ; the balance, however, in the aggre- 

 gate is not equal between these opposite pro- 

 cesses, a much larger quantity of carbon being 

 fixed by the decomposition of carbonic acid 

 gas and oxygen set at liberty, than there is of 

 oxygen absorbed and carbonic acid gas set free. 

 These acts are essential to the life and health 

 of vegetables ; their end and object appear to 

 be the preparation of their proper nutritive 

 fluids or cambium : the sap which reached the 

 leaves, colourless, not coagulable, without glo- 

 bules, mere water holding carbonic acid, 

 acetic acid, a muco-saccharine matter, and 

 various salts in solution, is in them converted 

 into a greenish fluid, partly coagulable, and 

 full of globules, which special vessels then 

 distribute for the growth and maintenance of 

 the different parts. 



The respiratory act is necessary, and goes on 

 without the aid or concurrence of the indi- 

 vidual among vegetables. 



Animals are no less dependent than vege- 

 tables on communication with the air of the 

 atmosphere, either immediately or mediately, 

 for a continuance of their existence, or the 

 manifestation of those acts whose sum con- 

 stitutes their lives. In the, very lowest tribes 

 the communication between them and the air 

 of the atmosphere takes place over the surface 

 of the body generally, without the intermede 

 of any particular organ or organs for the pur- 

 pose. The fluids absorbed into their bodies 

 are brought into contact with the atmospheric 

 air in those points where they approach the 

 external surface, and there appear to undergo 

 the changes necessary to fit them for being 

 convertecf into the substance of the animals 

 themselves. Simple as this process may ap- 



