116 



PRODUCTS, ADVENTITIOUS. 



Besides, M. Gendrin has forgotten to explain 

 why, if the pus-corpuscles escape from the 

 vessels, the blood-corpuscles, of much smaller 

 size, as they are, do not follow abundantly in 

 their track. M. Donne* some time since re- 

 vived the idea of conversion, believing that 

 he had seen red-corpuscles changed into puru- 

 lent in a mixture of pus and blood out of 

 the body: he was deceived by the physico- 

 chemical changes already referred to, which 

 pus, like various other fluids, effects in the 

 blood-corpuscles. 



The true doctrine of pyogenesis is a modi- 

 fication of that of " secretion " taught by 

 Simpson (1722), de Haen (1756), Morgan 

 (1763), Brugmans (1785), and John Hunter. 

 The direct microscopical evidence, upon 

 which it has been finally established, was ori- 

 ginally and mainly supplied by Wood, Gueter- 

 bock, and Henle. This evidence is to the 

 effect that, as a general fact, the generation of 

 the solid materials of pus takes place wholly 

 outside the vessels in a hyaline blastema. In 

 that blastema granules first appear ; subse- 

 quently, bodies of larger size form, either 

 independently of the granules or around 

 them, and, collecting in variable numbers, or 

 remaining single, present the characters of, 

 and actually constitute, the nucleus of the 

 pus-corpuscle. The involucrum, or cell-wall, 

 next forms ; and, at first clear and trans- 

 parent, subsequently grows granular. One of 

 the readiest plans of observing this series of 

 changes, is by using the exudation-fluid from 

 a blistered surface, but the same phenomena 

 may be traced on wounded surfaces. 



The elementary tissues of the body are not 

 at first altered in any appreciable manner by 

 the occurrence of suppuration among them-]-; 

 solution of their substance may at length be, 

 and frequently is, more or less completely 

 effected. This solution-process is of triple 

 nature : it is physical, in that mere maceration 

 aids in its production; chemical, in that in 

 certain unhealthy states of the system, solvent 

 agents, &c.J are generated in suppuration; 

 vital, in that the tissues themselves, in certain 

 constitutional conditions, lose partially or 

 completely their force of cohesion. 



4. MELANIC DEPOSIT. 



Black colouring mutter appears under va- 

 rious conditions as a morbid deposit. The 

 only kind strictly belonging to the present 

 head, is true melanic granule or cell-pigment, 

 more or less closely similar to natural pigment. 



Melanic pigment is essentially composed 

 of extremely minute granules, for the most 

 part contained within cells. The cells are of 

 various shapes, commonly rounded, however; 

 not commonly of caudate form, but often 

 showing a tendency to prolongation in one 

 particular direction. They very rarely con- 

 tain a nucleus. 



* Arch, de Med. Juin, 1836. 



f The first change discoverable under the micro- 

 scope seems to be loss of elasticity. 



I Prussic acid, according to Dumas. (Comptes 

 Rendus de 1'Institut, 1841. ") 



The cells are of blackish, brownish, bistre 

 or yellowish tint, the colour evidently depend- 

 ing on the granules. And these granules are 

 not confined to the cells, but are commonly 

 found, in multitudes, free ; when excessively 

 minute they are the subjects of molecular 

 motion. In some instances cells are not to 

 be discovered at all. 



Little is positively known concerning the 

 development of melanic- pigment, either of 

 the mode, whether exogenous or endogenous, 

 by which increase of cells takes place, or of 

 the relationship in which the cells and gra- 

 nules stand to each other; that is, whether 

 the cells are formed around the granules, or 

 the granules generated within the cells. But 

 while it is certain that the cells are deficient 

 in the attribute of permanency, and appear 

 of secondary importance (seeing that the pig- 

 ment character may exist in perfection in- 

 dependently of them through t the granules 

 alone), it seems very unlikely that they are 

 truly vegetative. Melanic cells never exhibit 

 any tendency even to cohere much less to 

 form the basis of a stroma. 



The chemical composition of this substance 

 is not known with accuracy. Analyses in 

 numbers no doubt have been printed, but 

 none of them are entitled to confidence, 

 either because they include the composition 

 of associated substances, organic and inor- 

 ganic, or because the black matter analyzed 

 was not really composed of cell-pigment. It 

 is probable, however, that the ultimate con- 

 stituents are the same, and associated in, at 

 least very closely, the same proportions, as 

 of the pigment of the choroid coat. Some 

 of the more important reactions of this sub- 

 stance, as set down many years ago by Henry, 

 may be substantiated readily, and have fre- 

 quently been confirmed by ourselves. A 

 " softened melanotic tumour " was experi- 

 mented on: 1. By filtering through paper, 

 much of the colouring matter remained on 

 the paper, and the colour of that which 

 passed through was rendered much less in- 

 tense; 2. Boiling does not destroy the colour, 

 not even when a little caustic potass has been 

 added ; 3. It is not changed by acids even 

 when heated, except by strong nitric acid, 

 which turns it yellow ; 4. A stream of chlorine, 

 passed through the liquid, destroys the 

 colour, and throws down light-coloured floc- 

 culi*; 5. A few grains of corrosive sublimate 

 (nitrate of mercury and muriate of tin also, 

 though more slowly,) precipitate the colour- 

 ing matter and leave the supernatant fluid 

 clear. 



Black cell-pigment occurs under two chief 

 conditions unassociated, or associated with 

 other materials. The former condition is ex- 

 cessively rare, and we have certainly never 

 seen it in the human subject, that is, we 

 have never seen a fluid or solid accumulation 

 of cell-pigment utterly unmingled with other 

 fluids or solids, natural or adventitious : it ap- 



* Chlorine water (which we have used) does 

 not actually destroy the colour, but diminishes its 

 intensity greatly. 



