40 ON THE PLACE OF MAN IN THE SCALE OF BEING. 



2. However difficult it may be for us, owing to our imperfect knowledge, 

 to draw the line in individual cases, it cannot be doubted that a boundary does 

 exist ; and, in general, a very simple mark will suffice to establish the dis- 

 tinction. This mark is the presence or absence of a Stomach, or internal 

 cavity for the reception of food. The possession of a stomach cannot be re- 

 garded, however, as in itself an essential distinction between the two kingdoms 

 (as some have represented it) ; for its presence is merely a result, so to speak, 

 of the nature of the food of Animals, and of the mode in which it is obtained. 

 Vegetables are dependent for their support, upon those materials only, which 

 they obtain from the surrounding elements ; carbonic acid, water and ammonia, 

 duly supplied to them, with a small quantity of certain mineral ingredients, 

 affording all the conditions they require for the production of the most mas- 

 sive fabrics, and the greatest variety of secretions. But these same elements, 

 if supplied to Animals, could not be converted by them into the materials of 

 organized structures; for they can only employ them as food, after they have 

 been united into certain peculiar organic compounds ; and Animals are con- 

 sequently dependent, either directly or indirectly, upon the Vegetable kingdom 

 for their means of support. Now they cannot incorporate any alimentary 

 substance into their own tissues, until it has been reduced to the fluid form; 

 hence they need the means of effecting this reduction, which are supplied by 

 the stomach. Again, they cannot be always in immediate relation with their 

 food ; they have to go in search of it, and need a store-room in which it may 

 be deposited during the intervals ; this purpose also is supplied by the stomach. 

 It is evident, moreover, that the powers of voluntary locomotion and sensa- 

 tion, which Animals enjoy, are connected with the peculiar nature of the food 

 they require; for if they were fixed in the ground, like Plants, they would 

 not be able to obtain that which they require for their support. It is true that 

 there are some, which seem almost rooted to one spot; but these have the 

 power of bringing their food within their reach, though they cannot go in 

 search of it. Such is the case with many Polypes, which use their outspread 

 tentacula for this purpose ; and with the lower Mollusca, which can create 

 currents by means of ciliary action. 



3. A distinction might probably be erected, between the Animal and Vege- 

 table kingdoms, upon the mode in which the first development of the germ 

 takes place. The seed of the Plant, at the time of fertilisation, principally 

 consists of a store of nourishment prepared by the parent for the supply of 

 the germ, which is introduced into the midst of it. The same may be said of 

 the egg of the Animal. In both instances, the first development of the germ 

 is into a membranous expansion, which absorbs the alimentary materials with 

 which it is in contact; and it prepares these by assimilation, for the nourish- 

 ment of the embryonic structure, the most important parts of which the 

 only permanent parts in the higher classes of Animals and in Phanerogamic 

 Plants are in its centre. Now in Plants, this membranous expansion (the 

 single or double cotyledon) absorbs by its older surface, which is applied to 

 the albumen of the seed, and takes it more or less completely into its own 

 substance. In Animals, this expansion is developed in such a manner, that 

 it surrounds the albumen, inclosing it in a sac, of which the inner surface 

 only is concerned in absorption. This sac is, then, the temporary stomach 

 of the embryonic structure ; it becomes the permanent stomach of tho liadi- 

 ata ; but -in the higher classes, only a portion of it is retained in the fabric of 

 the adult, the remainder being cast oil', like the cotyledon of Plants, as soon 

 as it has performed its function. Thus, then, the first nisus of Animal de- 

 velopment is towards the formation of a stomach, for the internal reception 

 and digestion of food; whilst the first processes of Vegetable evolution tend 

 to the production of a leaf-like membrane, which, like the permanent frond of 



