560 OF NUTRITION. 



eye will occasion atrophy of the optic nerve, and destruction of the optic gan- 

 glia will induce atrophy of the eyes and optic nerves. Even the bones of a 

 limb will suffer, in cases of atrophy of the muscles consequent upon disuse; for 

 in the case already cited ( 313) from Dr. J. Reid, the bones of the quiescent 

 limb only weighed 81 grains, whilst those of the exercised limb weighed 89 

 grains. It is an important fact, which was first pointed out by Mr. Paget, 1 that 

 when fatty degeneration is commencing in any tissue which is characterized by 

 the persistence of its nuclei, it is in the nuclei that the first alterations are 

 seen ; for they become pale and indistinct, and gradually disappear altogether, 

 almost before any other change is discernible in the contents of the cells or tubes 

 to which they appertain ; but in atrophy from mere decrease, this disappearance 

 of the nuclei does not occur. 



599. Reparative Process. The nutritive operations take place, with extra- 

 ordinary energy and rapidity, in the process of Reparation; by which losses 

 of substance, occasioned by injury or disease, are made good. In its most 

 perfect form, this process is exactly analogous to that of the first development of 

 the corresponding parts ; and its results are as complete in the one case as in 

 the otKer. In fact, among the lowest tribes of Animals, we find these two 

 conditions blended, as it were, together; for the process of reparation may be 

 carried in them to such an extent as to regenerate the whole organism from a 

 very small portion of it. In the Hydra or Fresh-water Polype, there would 

 seem to be scarcely any limit to this power ; for even if the body of the ani- 

 mal be minced into small fragments, every one of these can produce a new and 

 perfect being. In this manner, no less than forty have been artificially gene- 

 rated from a single individual. In ascending the Animal scale, we find this 

 reparative power less conspicuous, because limited in its exercise to particular 

 tissues and to comparatively insignificant parts of the body; and in Man, as in 

 other warm-blooded Vertebrata, the regenerative power is for the most part 

 restricted in its exercise, as Mr. Paget has pointed out, 2 to three classes of 

 parts; namely, (1.) "Those which are formed entirely by nutritive repetition, 

 like the blood and epithelia, their germs being continually generated de novo 

 in the ordinary condition of the body; (2.) Those which are of lowest organi- 

 zation, and (what seems of more importance) of lowest chemical character, as 

 the gelatinous tissues, the areolar and tendinous, and the bones; (3.) Those 

 which are inserted in other tissues not as essential to their structure, but as 

 accessories, as connecting or incorporating them with the other structures of 

 vegetative or animal life, such as nerve-fibres or bloodvessels. With these 

 exceptions, injuries or losses are capable of no more than repair in its limited 

 sense ; i. e., in the place of what is lost, some lowly organized tissue is formed, 

 which fills up the breach, and suffices for the maintenance of a less perfect 

 life." Yet, even thus restricted, the operations of this power are frequently 

 most remarkable ; and are in no instance, perhaps, more strikingly displayed, 

 than in the re-formation and remodelling of an entire bone when the original one 

 has been destroyed by disease. That this power is intimately related to that by 

 which the organism is normally built up and maintained, is evident, not 

 merely from the peculiar mode in which it is exercised its tendency being 

 always to reproduce each part in the form and structure characteristic of it at 

 the particular period of life, and not according to its embryonic type but also 

 from the fact that it is more effectual in the state of growth than in the adult 

 condition, and that it can do far more in the embryonic state, when develop- 

 ment as well as growth is taking place, than after the developmental process 



1 "Lectures on Nutrition," &c., in "Medical Gazette," 1847, vol. xl. pp. 145, 146. 



2 "Lectures on Reproduction and Repair," in "Medical Gazette," 1840, vol. xliii, p. 

 1022. 



