MALIGNANT TUMORS 425 



by the glands of the cutaneous structures of the cyst, and 

 resemble in composition sebaceous material, which is charac- 

 terized by containing a large proportion of cholesterin partly 

 combined with fatty acids. 



(/) " Butter " Cysts. In the mammary gland retention 

 cysts form, filled with products of alteration of the milk, 

 including butyric acid and lactose (Klotz 1 ), and these are 

 called "butter cysts" or milk cysts. Analysis of the contents 

 of such a cyst by Smita 2 gave the following results, as compared 

 with human milk : 



Cyst contents. Human milk. 



Fat 72.97 3.90 



Casein 4.37 0.63 



Albumin 1.91 1.31 



Milk-sugar 0.88 6.04 



Ash 0.36 0.49 



Water 20.81 87.09 



Fats consisted of Cyst . Cows , milk- 



Stearin and palmitin - . . 37.0 50.0 



Olein 53.0 42.2 



Butyrin 9.0 7.8 



Occurring independent of lactation usually, but not always, 

 are the " soap cysts," which contain chiefly calcium and mag- 

 nesium soaps, but also neutral fats, free fatty acids, and traces 

 of cholesterin (Freund 3 ). 



(2) MALIGNANT TUMORS 



The chief general features of the composition of these growths 

 have been considered in the discussion of the chemistry of tumors 

 in general (pages 412-420). A malignant tumor diifers from a 

 similar benign tumor chiefly in having usually a larger proportion 

 of the primary cell constituents, and a smaller proportion of the 

 secondary constituents and intercellular substances, since these are 

 largely the product of the functional activity of the cells, which, 

 in malignant tumors, do not often develop sufficiently to func- 

 tionate extensively. Hence malignant tumors usually show a 

 rather high proportion of the characteristic constituents of nucleo- 

 proteids ; i. e., phosphorus and iron. If rapidly growing, they 

 contain much potassium ; if undergoing much retrogression, little 

 potassium and a larger amount of calcium (Beebe, Clowes and 

 Frisbie). On account of the extensive disintegration, the 

 products of autolysis are usually much more abundant than in 



1 Arch. klin. Chir., 1880 (25), 49. 



2 Wien. klin. Woch., 1890 (3), 551. 



3 Virchow's Arch., 1899 (156), 151. 



