PACHYDERMIA LYMPHANGIECTATICA. 881 



affected skin, affords additional evidence that it is tlie superficial, 

 sub-papillary network of lymphatic vessels, which has undergone 

 partial ampulliform dilatation. The vesicles are roofed in by 

 the epidermis together with the papillary body. As a rule, the 

 detached portion of the papillary body contains from four to six 

 papillae ; in the smaller vesicles, these are still tolerably long and 

 slender ; in the larger ones, they assume a broader and shorter 

 form ; I have never seen them stretched to such a degree as 

 no longer to be recognisable. All the vesicles are lined witli 

 the well-known mosaic of endothelial cells ; and this places their 

 origin from dilated lymphatics beyond all doubt. We have still 

 to find out the special cause of the peculiar modification of the 

 anatomical appearances. I feel myself obliged to look for it in 

 the implication of the imstriped muscular fibres of the skin in 

 the hyperplastic process. 'SVe know that the tract of skin which 

 is peculiarly liable to be affected by pachydermia lymphan- 

 giectatica is also very richly endowed with involuntaiy muscular 

 fibres ; indeed the tunica dartos of the scrotum is an independent 

 muscular membrane (cf. Neumann on the Distribution of the 

 Fibres of Organic Muscle, in Wiener Sitzb. 1868, p. 651). 

 Now in the case which I had an opportunity of examining, and 

 which presented the anatomical features of the disease in 

 their most tj^pical form, there was a very distinct overgrowth 

 and proliferation of unstriped muscular fibres ; tliey were 

 grouped in well-marked, compact fasciculi, Aviiich permeated 

 the entire thickness of the corium — radiating obliquely from 

 below upwards in all imaginable directions. The corium indeed, 

 was made up of muscular and fibrous elements in nearly equal 

 proportions. Setting aside the likelihood of compression of the 

 lymphatic trunks by the actual contractions of this exuberant 

 muscular layer (of those trunks which, passing vertically 

 through the cutis, serve to connect the superficial with the 

 deeper network of lymphatic vessels), and the consequent am- 

 pullary dilatation of the superficial network; it cannot be denied 

 that a somewhat similar effect would needs be produced by the 

 mere elastic reaction of the muscular parenchyma, wlien this is 

 developed, as in the present case, in a region singularly incap- 

 able of yielding to the demands of new products, of whatever 

 kind, for more space. Hence I am led to beheve that the over- 

 growth of the muscular fibres is to be regarded as the chief 



