FORMATIVE POWER OP INDIVIDUAL PARTS. 553 



the whole series of Epithelial and Epidermic cells, which are thrown off with 

 little previous change, like the leaves of trees, their decay not taking place, for 

 the most part, until after they have become detached from the organism. But 

 the fact is altogether different with regard to those whose nutrition is interstitial, 

 especially the nervous and muscular tissues ; for the decomposition of these 

 would seem to occur in their very substance, its products being taken up by the 

 blood, and subsequently eliminated from it by organs appropriated to that pur- 

 pose. The evidence of this is seen, as regards Muscle, in the presence of crea- 

 tine, creatinine, inosite, and other undoubted products of regressive metamorpho- 

 sis, in the "juice of flesh ;" as regards the Nervous substance, however, no such 

 definite proof can be at present afforded, since its normal constitution has not 

 yet been sufficiently studied to enable the products of its decomposition to be 

 distinguished. There is one remarkable form of degeneration, however, which 

 is common to nearly all the tissues, and which seems to occur as a normal altera- 

 tion in many of them at an advanced period of life ; this consists in the conver- 

 sion of their albuminous or gelatinous materials into fat, thus constituting what 

 is known as " fatty degeneration/' That this change is not due to the removal 

 of the normal components of the tissues, and the substitution of newly deposited 

 fatty matter in their place, but is (in most cases at least) the result of a real 

 conversion of the one class of substances into the other, has been already pointed 

 out ( 40). And there are certain facts which indicate that this kind of degene- 

 ration is a part of the regular series of processes, by which tissues that have 

 served their purpose in the economy are prepared for being removed by absorp- 

 tion ; one of the most remarkable being the observations of Virchow 1 and Kilian 3 

 with regard to the fatty degeneration of the muscular tissue of the uterus after 

 parturition. So, as Mr. Paget has pointed out, the fibrinous and corpuscular 

 products of inflammation are often brought into a state fit for absorption, by pass- 

 ing through this intermediate stage ; the fibrinous substance being observed to 

 be dotted by granules, which are known to be oil particles by their peculiar 

 shining black-edged appearance, and at the same time losing its toughness and 

 elasticity, and being no longer rendered transparent by acetic acid j whilst the 

 lymph-cells present a similar increase of shining black-edged particles like 

 minute oil-drops, which accumulate until they nearly fill the cell-cavity, their 

 nuclei at the same time gradually fading and disappearing. 3 Thus, then, if the 

 fat, which is one of the products of this regressive metamorphosis, be absorbed 

 as fast as it is formed, and the effete tissue be replaced by a new production, 

 which seems to be the case with Muscles in a state of healthy activity, there is 

 no appearance of degeneration, and the nutrition is kept up to its normal stand- 

 ard. But if, from the advance of age or from the insufficient exercise of the 

 muscles, their nutrition take place less rapidly than their waste, whilst the pro- 

 ducts of their degeneration are still removed, simple atrophy is the result. If, 

 on the other hand, the general conditions being similar, the fat produced in 

 degeneration be not absorbed, but remain in the tissue (as is, perhaps, most 

 likely to happen when a copious supply of respiratory material is afforded by 

 other substances), an obvious " fatty degeneration' ' is the result. It may be 

 stated as a general rule that no absorption of the materials of tissue can take 

 place without a previous degeneration such as this, or a more complete decom- 

 position. There is no evidence that any healthy tissue is ever thus absorbed, or 

 that any preternatural activity of the absorbent vessels can ever (as formerly 

 supposed) be the occasion of a loss of substance ; in fact, so long as the vital 

 force is in active operation in a part, and its processes of growth and develop- 



1 " Verliandlungen der Gesellschaft fur Geburtshiilfe," Berlin, vol. iii. p. xvii. 



2 " Henle und Pfeuffer's Zeitschrift," vol. ix. p. 1. 



3 See Mr. Paget' s" Lectures on Inflammation," in "Medical Gazette, "1850, vol. xlv. p. 7. 



