294. 



STOMACH AND INTESTINE. 



Germ. ; ivrtpov, dr. ; Inte&linum, Lai.; Intestine, 

 Ital. Sp.; Intestin, Fr.*) 



What are called the organs of the animal 

 body consist of a diversity of tissues, so 

 grouped and united with each other as to 

 form a more or less continuous and aggregate 

 mass ; the functions of these various struc- 

 tures being also associated in a single general 

 purpose, which may be regarded as the sum 

 of their several actions on the system at 

 large. 



Among such groups of structures, there 

 is none more remarkable than that which 

 effectuates the series of processes collectively 

 termed DIGESTION. For other organs are 

 so far exclusively dependent on the blood, 

 as that many influences of the outer world 

 can scarcely reach them, except through 

 the medium of this fluid. Entrenched, as 

 it were, behind this the great river of ani- 

 mal life, they are secured from any but 

 the indirect action of t numerous physical 

 agents. But the organ of digestion lies out- 

 side this stream : and occupies a kind of 

 neutral territory, between life and matter, 

 where the various forces of both can co- 

 operate for its benefit, in equal and har- 

 monious conjunction. Or rather, let us say, 

 the digestive canal is the threshold of the 

 House of Life, where dead matter is first 

 endowed with those properties which enable it 

 to become a living constituent of the animal 

 body. 



The group of organs before us has indeed a 

 special relation to the animal. For although 

 digestion is usually enumerated amongst 

 those general or organic functions which are 

 shared in by everything that has life, vege- 

 table as well as animal, still the means by 

 which the process is effected in these two 

 forms of organization, constitute as important 

 a distinction between them, as the mere pre- 

 sence or absence of other functions. So that, 

 the digestive cavity is, on the whole, as charac- 

 teristic of the animal, as the organs of loco- 

 motion and innervation of which it is the 

 exclusive possessor. 



How far the so-called vegetative functions 

 are really alike, or even comparable to each 

 other, in the two kingdoms of nature, it is not 

 our object here to inquire. As little do we 

 wish to introduce, what some might perhaps 

 think less out of place, a detailed comparison 

 between the digestive functions of the plant and 

 animal. But as the cavity which it is our 

 express object to describe is all but univer- 

 sally present in the latter, and absent from 

 the former organization, it seems desirable 

 briefly to contrast them in this respect. 



* In respect to the etymology of these names we 

 may conjecture as follows: The word y<rnij is 

 radical. The stomach is so called from its connection 

 with the mouth (>*). Miiw and mar/en are de- 

 rived from its relation to food (meat). Intestine, 

 EI/TEJCV, eiitrail, ventriculns, (and i/nrin ?) connote its 

 internal and hidden position. Boicel (botellus), and 

 tripe ( T ?= TS " / ), refer to its convoluted or tortuous 

 form : gut (geotan, Anglo-Saxon, to pour), to its car- 

 rying ilucnt contents. 



In the animal, a highly azotized composition is 

 connected with, and probably essential to, 

 an active life; which, in its turn, implies a rapid 

 waste of substance. On the other hand, the 

 plant lives slowly, wastes little, and contains 

 but a small quantity of azotized material. 



The food of each appears to correspond 

 with these requirements. That of the plant 

 is, in great part, inorganic ; consisting mainly 

 of compounds which pervade the soil that 

 surrounds its roots, or the air which bathes 

 its leaves. While that of the animal is or- 

 ganic : L e. the substances which compose it 

 are the products of a previous organization. 



The elaboration of the food repeats the 

 preceding contrast. The plant builds up in- 

 organic into organic matter ; a process of 

 chemical synthesis, which may well be effected 

 with great difficulty, and by slow stages. While 

 the animal scarcely does more than convert one 

 proximate principle into another ; a meta- 

 morphosis which involves no change of com- 

 position, and the facility of which is but par- 

 tially counterbalanced by its requisite rapid- 

 ity and amount, and the delicacy of its ad- 

 justment. 



The agents of these processes are also 

 susceptible of comparison. For in the vege- 

 table they appear to be closely connected with 

 various external forces, such as light and heat; 

 while in the animal they seem more inherent 

 to the organism.* 



And in both, the site of the elaboration or 

 change in the food corresponds to those situa- 

 tions where the above agents are most readily 

 applicable: viz. in the plant, to the leaves 

 and other green parts of its surface; in the 

 animal, to a cavity in its interior. The pre- 

 sence of such a cavity not only permits the 

 less frequent application of nutritious substance 

 to be compensated by the ingestion of large 

 quantities at particular times ; but, while it 

 thus meets the peculiar requirements of an 

 animal organism, also allows of that loco- 

 motion which is so necessary to the mere 

 prehension and selection of its scarcer food. 

 Its subjection to volition renders ingestion a 

 work of rapid and powerful mechanical force, 

 in place of a slow physical imbibition. Ami 

 finally, the same internal situation which 

 directly subjects its contents to the agents of 

 the digestive metamorphosis, also isolates 

 them from all surrounding objects, besides 

 favouring the temperature often necessary to 

 the operation.-)- 



* Traces of this contrast hetween the animal and 

 plant, during life may be found in those processes of 

 putrefaction and eremacausis which respectively 

 effect their dissolution after death. 



f Hence, instead of a digestion corresponding to 

 that of the animal, the plant presents us with a pro- 

 cess in which mere reception is so predominant, that 

 we might almost compare it with the absorption 

 of the chyme and chyle into the blood. As a kind 

 of fanciful corollary to this, we might regard the 

 crust of the earth, and the atmosphere which sur- 

 rounds it, as forming a common stomach or recep- 

 tacle of food for the whole vegetable kingdom. For 

 they include, or receive, detain, and give up, the che- 

 mical food of the plant ; in quantities which, though 



