ABSORPTION. 



organic matter is in a state of decomposition, taints 

 the air with poison. 



The action of the air upon plants, and upon ani- 

 mals in breathing, appears also to be analogous to 

 absorptionto be, in fact, the identical process ; and 

 as the nilnx/en of the air seems to be only the vehicle 

 in which the oxygen is in these cases conveyed to 

 the plant or the animal, we may thence infer that 

 those two component parts of the atmosphere 

 are merely mechanically mixed, and not chemically 

 united. That holds in the case of animals which 

 breathe water by gills, as well as in that of those 

 which breathe air by lungs ; for the fish cannot 

 live in water that has been wholly deprived of 

 air, any more than a land animal can live in an 

 exhausted receiver. It is a general law of nature, 

 to which there are no known exceptions, that com- 

 bination can be separated but by some action more 

 powerful than that by which it was united. But 

 the formation of water from its elementary gases, 

 oxyiren and hydrogen, has not, in any instance with 

 which we are acquainted, taken place without an 

 intensity of action, which no known plant or animal, 

 or any part of the one or the other, could bear ; and, 

 therefore, we cannot reasonably believe that any of 

 them can decompose water, so as to avail themselves 

 of either of its elements, by any process at all analo- 

 gous to absorption, whether by the surface generally, 

 or by any specific surface, such as that of the cells of 

 lungs, or the fibres of gills. 



Hence, in what part soever of nature it takes place, 

 we must regard absorption as a merely mechanical 

 process an action as between surface and surface, in 

 which, how minutely soever the substances may be 

 mixed with each other, there is no chemical action, 

 no decomposition of an old substance, and no form- 

 ation of a new one. 



In vegetables the process is simple, and it appears 

 to be the only one by which matter is added to the 

 leafy part of the vegetable. They receive their food 

 wholly by absorption ; and the process of assimilation 

 takes place afterwards. In animals the case is differ- 

 ent ; for though the surfaces of most animals are 

 capable of absorbing, and the matter which they thus 

 absorb sometimes, in part at least, serves as food ; yet 

 the food, properly so called, of even the most simple 

 animal, is first taken into some sort of a stomach, 

 ami there assimilated, before it is absorbed. 



There is still this further distinction between absorp- 

 tion in vegetables and in animals, that all which the 

 vegetable absorbs trues to additional growth or in- 

 rrease- of substance, either in the structure of the in- 

 dividual plant, or in the formation of seeds, or other 

 germs of new ones of the same species. Plants, no 

 doubt, irive out trases ; but there is not in any plant 

 u means of taking up the waste of the system, and 

 replacing' it by new matter. Plants do, under peculiar 

 circumstances, form accumulations of pulpy or starchy 

 matter, which is sometimes called vegetable ALBUMEN; 

 and the act of cultivating vegetable substances for 

 food chiefly consists in making them produce useful 

 nutriment, rather than stems and leaves ; but still, 

 there is no power in the vegetable to absorb that which 

 has once formed part of its original structure, and re- 

 place it by new matter, which shall again perform the 

 function, as is the case in the animal economy. 

 When the sap of the year has once granulated into 

 cambium, and that cambium has ripened in the 

 autumn into wood and bark, there is no return 



of it to the living action of the tree. It lingers 

 for a longer or shorter time, according to the species, 

 as ALBUMEN, before its final consolidation into " heart 

 wood ;" but when its one season is passed over, it 

 buds and blossoms no more ; and thus, how long 

 soever the tree may last, it is still but an annual, as 

 a growing vegetable of the same localised matter. 

 Some trees, indeed, have the power of obliterating the 

 remains of small lateral branches, after new layers of 

 wood have grown over them ; as we find many trunks 

 of pines and other trees without any appearance of 

 knots in the wood, though we know, from the habits of 

 the species, that they must have at one time been 

 branched at short intervals, all the way from the root 

 upwards. But the obliteration of these and also of 

 the pith in many trees takes place in the wood, where 

 we cannot examine it, and therefore we cannot say 

 whether it is produced by absorption or by simple 

 pressure. Generally speaking, vegetables have not 

 the power of removing any part by absorption, how- 

 ever much that part may disfigure or injure their 

 system ; the gnarl upon the bole of the deciduous 

 tree, and the union of shoots which sometimes pro- 

 duces so singular an appearance in pines, are never 

 obliterated. In animals, on the other hand, there 

 appears to be an almost unlimited power of absorp- 

 tion. The waste of all parts of the system is conti- 

 nually taken up ; and many unnatural accumulations 

 of matter are absorbed by the action of the system, 

 w ithout the aid of any artificial application. 



In many subjects, both animal and vegetable, there 

 are seasonal accumulations of matter, which are again 

 absorbed, as will be explained at length in the article 

 HYBERNATION ; and in some animals there are accu- 

 mulations at certain ages, which are absorbed for the 

 support of the system when the powers of assimilation 

 begin to fail, or when they are weakened by disease. 

 These absorptions extend not merely to the fat of the 

 animal, but to all the soft parts ; and it is truly said of 

 certain diseases and conditions of the body, that they 

 " eat the flesh off" the bones." Nay, the bones them- 

 selves do not escape the ravages either of disease or 

 of time ; for that bending of the body and shortening 

 of all its dimensions which take place when, in the 

 extreme of life, man passes into " the sere and 

 yellow leaf," are occasioned by absorption of the 

 bones not merely of their cartilaginous part, but 

 of the salts of lime ; and this absorption is some- 

 times so excessive, that the lime thus taken into 

 the circulating blood is precipitated upon the coats of 

 the blood vessels, and even upon the heart itself, form- 

 ing what are termed ossifications. There have been 

 instances in which one part of the body has had the 

 blood vessels thus converted into tubes of bone, while 

 the rest retained the power of all its functions ; and 

 also instances where, in consequence of ossifications of 

 the heart or the proxiniate vessels, the system has 

 repeatedly stopped till put in motion by the applica- 

 tion of ardent spirits or other strong stimuli ; from 

 which it appears that absorption is among those func- 

 tions of the animal system which last the longest. It 

 is indeed very probable that absorption continues even 

 after life is extinct ; for though it takes place largelv 

 in the living structure, it cannot be said to be, in itself, 

 a function of life, or a display of the living principle. 

 While the living principle maintains its activity, it 

 controls the power of absorption; and the different 

 tissues with which the several parts of the body are 

 covered have it in different degrees. The coating of 



