PART II.] Nature of the Pigmentary Deposits. 385 



others ? Certainly the forms under which the disease manifests itself are in many 

 ways different from those ordinarily met with : it is characterised by being localised 

 to certain districts, and by the fact that only certain parts of the body, as far as 

 we at present know, are liable to be affected ; and more than all, the morbid 

 product of one, or rather two, of its varieties, the black and the pink, are so 

 particular, as to enable it to be distinguished at once from all other affections. 

 But that these peculiarities should of themselves be sufficient ground for forming 

 any conclusions with reference to the cause of the affection, is not supported by 

 the observations which we have made. 



The reader of the foregoing chapters will have observed that three of the peculiar 

 morbid products, described as various stages in the develoj^ment of a peculiar fungus 

 the assumed cause of the disease, have been very carefully investigated, m^., the 

 roe-like bodies ; the pink particles, and the black masses. 



The first of these we have shown to be fat in various modified forms ; the second 

 were found to be pigmented concretions — not the slightest trace of a fungus, or 

 of other vegetable organisms, being present in either; and the third we have 

 shown to consist of degenerated tissue, mixed to a greater or less extent with 

 black pigment and fungoid filaments. To account for the presence of the two 

 latter ingredients is in reality the most difficult problem connected with the affection. 



As regards the actual lesions produced in the tissues, it will have been 

 observed that neither of these two latter ingredients are essential, seeing that, with 

 the exception of the physical characters of the morbid products, no marked dis- 

 tinction exists between the pale and the black varieties. Similar tissues are affected 

 in both, the cavities and channels are alike, and the similarity extends even to the 

 peculiar mammillated orifices by which they open on the surface. These circum- 

 stances of themselves absolutely negative, in our opinion, the view that anything 

 which may be found in connection with one variety, and not in connection with 

 the other, can be referred to as the specific cause of either. Why these morbid 

 substances should present these anomalies is a totally different question and one 

 which is not within our province to discuss. 



The occurrence of pigmentary deposits in animal tissues is by no means a rare 

 circumstance. Our knowledge as to whence the pigment is derived is not yet very 

 exact, but it is generally believed to be derived from the blood. Its behaviour 

 under the influence of re-agents is however well known, and we have found that 

 the pigment in the dark substance, when treated with re-agents, manifests properties 

 similar to those of ordinary pigment. The presence of iron in the pigmented 

 substance of the Madura-disease, which both Mr. Wood's analysis and our own 

 revealed, is a significant fact, seeing that iron is a constant component of black 

 pigment, a circumstance which, in our opinion, points, almost unequivocally, to the 

 fact that the pigmented substance under consideration originates from the same 

 material as the pigmentary deposits ordinarily met with in animal tissues. 



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