NUTRITION. 81 



given form of tissue, nature does not at once unite the organic 

 molecules in that form, but that she first creates in a structureless 

 fluid, or in previously existing cells by a definite process, round 

 vesicles or cells, and subsequently transforms these into the various 

 elements of the organic textures. 



The process of nutrition varies greatly according to age, consti- 

 tution, idiosyncrasy, state of health, &lc. It is most rapid in youth, 

 during the growth of the body ; it is greatly less in old age ; but 

 differs widely with reference to particular organs. Morbid condi- 

 tions, excessive bodily and mental efforts, the depressing emotions, 

 such as care and sorrow, are all incompatible with perfect and pow- 

 erful nutrition, and induce wasting of the several organs. As a 

 general rule it may be stated, that the greater the demand for the 

 functional activity of the organ or tissue, the more energetic is its 

 nutrition, and vice versa. Whenever the amount of nutritive mate- 

 rial deposited in a tissue or organ is more than sufficient to supply 

 the waste, the part becomes h7/pertrophied or over-nourished. The 

 term hypertrophy signifies excessive nutrition. It differs from 

 healthy nutrition only in degree. It consists in the augmentation of 

 one or more of the natural constituents of an organ, in such a man- 

 ner that the newly formed parts are continuous with those already 

 existing, and cannot be anatomically distinguished from them. Hy- 

 pertrophy is never known to affect the whole body, to a degree suf- 

 ficient to constitute disease. But examples of hypertrophy of parti- 

 cular organs or tissues are very common. Atrophy, or diminished 

 nutrition, is exactly the reverse of the condition just described, but 

 is more generally a morbid operation, and may affect either the 

 whole body or individual parts. It takes place whenever the waste 

 of the tissues is more rapid than their replacement by nutrition. 



The nutritive operations, by which lost parts are repaired, take 

 place with great activity. In its most perfect form, this process is 

 analogous to that of the first development of the corresponding parts, 

 and its results are as complete in the one case as in the other. 



The reparative process was formerly thought to depend on the 

 existence of inflammation ; it can be shown, however, that in the 

 majority of instances inflammation is injurious rather than beneficial. 



" That the powers of reparation and reproduction are in proportion 

 to the indisposition or incapacity for inflammation; that inflamma- 

 tion is so far from being necessary for the reparation of parts, 

 that in proportion as it exists, the latter is impeded, retarded, or 

 prevented ; that, when inflammation does not exist, the reparative 

 power is equal to the original tendency to produce and maintain 

 organic form and structure; and that it then becomes a natural 

 function, like the growth of the individual, or the reproduction of 

 the species."* 



• Treatise on Inflammation, p. 7, by Dr. Macartney. 



