232 THE MICROSOPIST. 



men, and identical with casein. Thus we have in the 

 living and dead cell a circle of metamorphoses, from casein 

 of milk to albumen of blood, thence to bioplasm, to formed 

 material of cells and of intercellular substances, to mucus 

 or colloid, and finally to casein. 



III. NEW FORMATIONS. 



To the surgeon the most important of these are tumors, 

 excrescences, hypertrophies, or overgrowths. The nomen- 

 clature of such growths is, however, greatly redundant 

 and often confusing. Some are named from the character 

 of their contents as apparent to the eye, as hygroma (like 

 water), melanoma (black pigment), chloroma (green ditto), 

 hsematoma (blood), colloma (glue), steatoma (lard), athe- 

 roma (gruel), meliceroma (honey), cholesteatoma (cho- 

 lesterin), sarcoma (flesh), neuroma (nerve), encephaloma 

 (brain), myeloma (marrow), schiroma (marble), etc. 



Paget classified tumors as follows : 



I. Innocent. 



1. Cystic: Simple, compound, proliferous. 



2. Solid: Fatty, fibro-cellular, fibrous, fibroid, cartilag- 

 inous, myeloid, osseous, glandular, and vascular. 



II. Malignant: Infiltrating, ulcerating, multiplying. 



Yirchow's nomenclature is based on the divisions of 

 hypertrophy, homeoplastic formations, and heteroplastic 

 formations. 



Histologically, the questions of origin and structure 

 chiefly concern us. Such a study may yet lead to a true 

 classification and rules of diagnosis. Yirchow held that 

 cells multiply by division at the place of the tumor, so 

 that the newly-formed tissues substitute a certain amount 

 of normal constituents. Cohnheim's wandering cells, how- 

 ever, show that formative elements may come from a dis- 

 tance, although local formation is also possible. Strieker 

 shows in inflammation a division of both wandering and 



