PIGMENTATION. 63 



Growths) shows us that a morbid state of the blood may exist, in 

 consequence of which cell-growth, on a large scale, may take 

 place in the most various regions of the body, the newly-formed 

 cells being wholly or partially filled with granular pigment of a 

 brown or black hue. The mechanism of this coloration is the 

 same as that of the cells of the rete Malpighii, choroidal epithe- • 

 Hum, &c. Indeed, the primary tumour is usually developed in 

 the choroid or the skin. The cells get their pigment from that 

 which is diffused throughout the nutrient fluid, and also, according 

 to 0. Weher, from capillary extravasations which may concur with 

 the other changes. Be this as it may, the progress of the pig- 

 mentation, after the stage of diffuse imbibition, is the same here 

 as elsewhere. The pigment is condensed and precipitated. The 

 colourless sarcoma-cells are converted into pigmented sarcoma- 

 cells. No one will deny that these pigmented sarcoma-cells 

 retain their most destructive vital properties, and make use of 

 them ao-ainst the oro-anism. 



I do not believe that we are justified in speaking of a pig- 

 mentary metamorphosis in the same sense as of a fatty meta- 

 morphosis. For even though we may find in the juice scraped 

 from melanotic tumours minute particles of pigment in countless 

 numbers, together with cells in which the pigment-granules may 

 be seen to exhibit dancing movements, and from which they may 

 be seen to escape under our ^-ery eyes, yet we are not justified in 

 inferring anything beyond an accident such as ultimately befalls 

 all sarcoma-cells ; moreover the numerous oil-globules which 

 are scattered among the pigment-granules, but which are not 

 easily to be distinguished from them, render it probable that we 

 have really to do with a fatty metamorphosis. 



§ 60. Besides hasmatin we must include the colouring-matter 

 of the bile among the sources of abnormal pigmentation. If we 

 were justified in assuming the derivation of bile-pigment from 

 the colouring-matter of the blood, then biliary may be regarded 

 as a mere variety of ha^mic pigmentation. It is met with only 

 in those organs which produce and excrete the bile. Suppose 

 for a moment, that jaundice (icterus) is a pigmentary infiltration. 

 In jaundice the bile-pigment, together with the other constituents 

 of the secretion, is reabsorbed into the blood : hence, as long as 

 the condition lasts, all the tissues of the body which are within 

 reach of the nutritive fluid assume a yellow hue. Never, or 



