OF THE STOMACH. 145 



this same apparatus for digestion has also parts superadded for the pur- 

 poses of digesting ; so that the parts preparatory and subservient to 

 digestion, become more complicated, and indeed so much so, that there 

 is hardly any system in an animal more complicated in itself; and when 

 we consider the varieties of these complications which take place in the 

 various animals, they appear to be almost without end. 



It is these complications and varieties that we mean to consider, and 

 reduce, as far as they will admit, to their several classes. 



The parts subservient to digestion in the complicated animals bear a 

 great relation to the other properties of the animal*. 



In classing the organs of digestion in the complicated animals, many 

 parts are to be considered which appear from a slight view of the sub- 

 ject to be only secondary, and therefore might be thought necessary to 

 be considered apart : but we shall find that many of these parts have 

 peculiarities, and these are adapted to the peculiar food and pecidiar 

 mode of getting it, and not at all belonging to simple digestion in 

 particular. 



These superadded parts, which have their mechanism adapted to the 

 way of life with respect to digestion, are the powers of mastication, — 

 in some, reservoirs, — the varieties of stomachs, — whether or not a 

 caecum, and of what kind, — and colon ; so that in classing the organs 

 of digestion, we must consider teeth, stomachs, caecums, and colon. 



The stomach varies less than either teeth, caecum, or colon. One can 

 easily see a reason why the teeth should vary according to the mode of 

 procuring the food, and according to the food ; and one can easily con- 

 ceive why the stomach need not vary much, because it can only be 

 considered as a bag ; but why so much dependence is to be had upon 

 the caecum and colon, is not so easily conceived. In classing stomachs, 

 it might be thought proper to take in all these relative parts ; but that 

 method would breed confusion. Therefore I shall class all the different 

 stomachs with their varieties ; and in classing the other parts they 

 must be referred to their respective stomachs. This will appear most 

 natural when we consider that there are many stomachs that have no 

 relative parts, which I shall naturally begin with, as the first class. 



Our first class is the simple stomach with one opening, which I call 

 Regurgitators 1 . 



* Animals in general might be tolerably well classed by these organs, most being- 

 reducible to a few general classes, which again admit of many subdivisions. 



1 [As in the Hydra, or fresh-water polype, and the Actinia ; the other classes of 

 stomachs, as they rise in the scale of complexity, may be studied in the Hunterian 

 Preparations, Nos. 409 to 590 inclusive. — Physiological Catalogue, vol. i. 4to, pp. 

 114-181.] 



I 



