248 LECTURE X. 



Of the well-known discoloration of the skin by silver 1 

 need not speak here. 



Another instance is afforded us by gout. If we exa- 

 mine the concretions (tophi) in the joints of a gouty per- 

 son, we find they are composed of very delicate, needle- 

 shaped, crystalline deposits of all possible sizes, and con- 

 sisting of urate of soda, with at most here and there a 

 pus- or blood-corpuscle lying between them. We have 

 here therefore also, as when silver has been employed, 

 to deal with a material substance which is usually ex- 

 creted by the kidneys, and that indeed not rarely in such 

 large quantities, that deposits form even within the kid- 

 ney itself and large crystals of urate of soda accumulate, 

 'especially in the uriniferous tubules of the medullary 

 portion, so as sometimes to lead even to an occlusion of 

 the tubules. If, however, this secretion does not pro- 

 ceed in a regular manner, the immediate result is an ac- 

 cumulation of urates in the blood, as has been shown in 

 a very able manner by Garrod. Then at last deposits 

 begin to form at other points, not throughout the whole 

 body, nor uniformly in all parts, but at certain definite 

 points and in accordance with certain rules. 



Here we have to do with very different forms of meta- 

 stasis from those with which we became acquainted 

 whilst considering the nature of embolia. That the 

 changes which ensue in the substance of the kidney, in 

 consequence of the absorption of silver from the stomach, 

 accord with what has in pathology since times of old 

 been termed metastasis is unquestionable. This consists 

 in a transferrence of matter from one spot to another, so 

 that the same substance which had previously been pre- 

 sent in the first comes and lodges in the second, and the 

 secreting organ takes up minute particles of the matter 

 into its own tissue. This is what we find constantly 



