66 MICROSCOPICAL DIAGNOSIS. 



cells. At this stage it would be impossible to tell the future of the 

 growth. Like the small cells of the embryo, they are entirely un- 

 differentiated. These cells may be the round cells of a sarcoma or 

 the cells of connective tissue. 



As soon as a tumor is completely developed it is liable sooner 

 or later to undergo some of the forms of degeneration. If it has 

 been of short duration, attained a considerable size, and if it is 

 composed largely of cells, then it will undergo these change's all the 

 more rapidly. If it has been of slow growth and its elements are 

 developed into tissue, then it will not be liable to degenerate. Fatty 

 degeneration is most commonly met with. This is probably due to 

 the fact that in the rapid formation of new tissue there is not a pro- 

 portionately new formation of blood-vessels, and as a result of the 

 insufficient circulation and want of nutritive material, the fatty 

 metamorphosis occurs. 



Tumors may also undergo pigmentary degeneration, usually 

 from a deposit of melanin. This is a black, or nearly black, sub- 

 stance found physiologically in. the skin and eye. It is seen either 

 as free granules in the tumor or deposited in the cells. It does not 

 appear to be at all susceptible to reagents, and its origin is probably 

 the same as that of haematoidin. In caseation the fluids are ab- 

 sorbed and the elements are dried up, changed into a yellowish 

 cheesy material, which process may continue until the whole mass 

 may become surrounded by a capsule of fibrous tissue. In calcifi- 

 cation, small calcareous particles are infiltrated through the mass. 

 Sometimes softening liquefies the whole mass into a thin liquid, 

 which under the microscope is seen to consist of broken clown ma- 

 terial, granular matter, fat, etc. 



Colloid and mucoid degenerations also occur when the albumi- 

 nous ingredients are transformed into substances chemically resem- 

 bling mucin and an allied colloid material. 



A tumor is malignant when it has a tendency to recur m the 

 same or some distant place after its removal. 



It is innocent when this tendency is not present. The term 

 ''malignancy," then, is purely a clinical one and does not refer to 

 any property of the growth to destroy life. The heterologous char- 

 acter of a growth is an evidence of its malignancy. 



In the examination of tumors the fresh cut surface should 

 be scraped and this examined for cells : their shape, number, size, 



