FUNCTIONS OF VEGETATIVE LIFE. 



the rest of the nervous system. This condition may be experimentally imitated, 

 however, by the removal of the brain, in many of the lower animals, whose 

 bodies will sustain life for many months after such a mutilation; but this can 

 only take place, when that food is conveyed by external agency within the 

 pharynx, which they would, if in their natural condition, have obtained for them- 

 selves. . A similar experiment is sometimes made by Nature for the Physiologist, 

 in the production of foatuses, as well of the human as of other species, in which 

 the brain is absent; these can breathe and suck and swallow, and perform all 

 their organic functions; and there is no assignable limit to their existence, so 

 long as they are duly supplied with food. 1 Hence we may learn the exact nature 

 of the dependence of the Organic functions upon those of purely Animal life ; 

 and we perceive that, though less immediate than it is upon the simple excito- 

 motor actions of the nervous and muscular systems, it is not less complete. On 

 the other hand, the functions of animal life are even more closely dependent 

 upon the Nutritive actions, than are those of organic life in general ; for many 

 tissues will retain their several properties and their power of growth and exten- 

 sion, for a much longer period after a general interruption of the circulation, 

 than will the Nervous structure; which is, indeed, instantaneously affected by 

 a cessation of the due supply of blood, or by the depravation of its quality 

 ( 536). 



2. Functions of Vegetative Life. 



374. As a certain change of composition of the Organized fabric is a necessary 

 condition of every manifestation of its Vital activity, it is obviously requisite 

 that a provision should exist for the replacement, by new matter, of all those 

 particles, which, having lost their vital endowments, are in process of return 

 to the condition of inorganic matter. And hence, of course, every increase in 

 the activity of the Animal functions becomes a source of augmented demand for 

 nourishment; provided, at least, that such increase does not go to the extent of 

 exhausting the vital energies, and thus of preventing the due performance of 

 the Nutritive functions. A constant supply of Aliment is therefore needed for 

 the maintenance of the body, after it has arrived at its full development. The 

 effects of the process of waste and decay, uncompensated by that of renovation, 

 are seen in starvation and in diseases of exhaustion ( 416); in which there is a 

 gradual diminution in the bulk of nearly all the tissues of the body, so that, 

 before death supervenes, the total reduction in weight is very considerable. 

 But in the growing state of the organism there is, of course, an additional 

 demand for Aliment, to supply the materials for the extension which is continu- 

 ally taking place in it. This, however, does not make so great a difference as 

 it might appear to do, in the supply of food which is required. For if the abso- 

 lute addition which is made by growth to the body in any given time, be com- 

 pared with the amount of change of composition which takes place in the same 

 period the latter being judged of by the quantity of food consumed, and by the 

 amount of excrementitious matter which passes off by the lungs, liver, kidneys, 

 skin, &c. it will be found to bear but a very small proportion to it. The fact 

 is rather, that, during the whole period of growth, there is (so to speak) a con- 

 tinual remodelling of the entire fabric; the life of each part being brief, in order 



1 A very remarkable case has been mentioned to the Author by his friend Mr. Wallis of 

 Hull; the subject of which has never, from the time of his birth, exhibited any distinct 

 indication of consciousness, and has yet, by sedulous care, been reared to the age of ten 

 years. There is no appearance of any malformation about the Brain, and yet it must ob- 

 viously be functionally inactive ; for no movements have ever been witnessed, which seem 

 to proceed from any higher centre than the Medulla Oblongata. Even in the administra- 

 tion of nourishment, it is necessary that the food should be carried back into the pharynx, 

 so that it may be grasped by the reflex action of its constrictors. 



