CANCER-CELLS. 



137 



lignant, but it often forms a part of cancerous and other malignant 

 growths. Pigment-cells developed on patches of skin (most fre- 

 quently of the forehead or other part of the face) constitute the 

 disease called ephelis hepatica; it being usually associated with 

 disease, often merely functional, of the liver. A different form of 

 deposit of pigment on the skin is also mentioned by Queckett, in 

 which it could be brushed off from the surface with a camel's-hair 

 pencil. It is believed that the face only is liable to this form of 

 deposit; and its actual existence is to be distinguished from some 

 other pigment purposely applied by the patient (usually a female) 

 to deceive the medical attendant. 



Moles and freckles, when congenital, are due to a deposit of pig- 

 ment-cells, from a cause not understood. 



The deposit of pigment sometimes occurring in cases of acne has 

 already been mentioned. 



Fig. 75. 



II. CANCER-CELLS. 



Cancerous masses consist of the four following elements, in addi- 

 tion to bloodvessels : 



1. A matrix of homogeneous substance, either hyaline or gran- 

 ular. 



2. Fibres more or less approaching those of white fibrous tissue 

 in appearance. 



3. A great variety of cells and nuclei, some of which are gene- 

 rally regarded as peculiar to cancer. 



4. A peculiar cream-like fluid, termed the "cancer-juice." 

 These elements vary extremely in their proportion in the different 



forms of cancer, of which three are 

 usually designated : 



1. Scirrhus, or fibrous cancer, in 

 which the homogeneous matrix and 

 the fibres, one or both, predominate. 

 (Fig. 75.) 



2. Encephaloid, or cellular cancer, 

 being constituted mainly of cells. 

 (Fig. 76.) 



3. Colloid cancer, in which there 

 is a predominance of a peculiar ge- 

 latinous fluid. 



These three forms are often found 

 coexisting in the same cancerous 

 mass. Melanotic cancer is distin- 

 guished merely from having pig- 

 ment-cells added to the cancer ele- 

 ments. (Fig. 77.) 



Neither the homogeneous matrix caucer-ceiis m fibrous stroma. 



