502 THE CHEMISTRY OF TUMORS 



nin), melanotic tumors may contain enzymes oxidizing tyrosine, epine- 

 phrin, pj^rocatechin, or other related aromatic substances, with the 

 formation of pigmentary substances. Catalase is low in tumor tissues 

 (Blumenthal and Brahn). (See also, Autolysis in Tumors, chap, iii.) 



Other enzymes are also present in tumor cells. Buxton '^^ exam- 

 ined a large number of tumors for their enzymes by the plate {aiixan- 

 ographic) method, and found considerable variations in different 

 growths. All contained amj'lase (splitting starch) and lipase (split- 

 ting butyrin). IMost, but not all, tumors coagulated milk and liquefied 

 casein, and also liquefied gelatin (rennin, proteases). Peroxidase was 

 nearly ahvays, and catalase always, present. Digestion of fibrin, co- 

 agulated seinim, and coagulated egg albumen could not be observed. 

 Practically all tumors split glycogen. Tj-^rosinase could not be demon- 

 strated. The fact that early embryonic tissues were found poor in 

 enzymes ""^ speaks against the common assumption that tumors repre- 

 sent strictly an embryonic formation, but Long "^ found that xanthine- 

 oxidase, which in normal development does not appear until late in 

 fetal life, was absent from primary- carcinomas of sheep livers, al- 

 though normal adiilt sheep liver tissue is rich in this enzyme. 



]\lacFadyen and Harden ^- studied the juices obtained by grinding 

 up tumor cells made brittle by liquid air, and found by direct meth- 

 ods (chiefly in breast cancers) invertase, maltase, amylase, proteases 

 acting in both acid and alkaline solutions, catalase, oxidase, with per- 

 haps traces of lipase and peroxidase, but no lactase. 



Tumors arising from the gastric mucosa, according to AYaring,'^^ 

 contain both pepsin and rennin ; those from the pancreas, both pri- 

 mary and secondary growths, contain trypsin, steapsin, amylase, and 

 rennin. 



(5) Internal Secretion. — If tumors are derived from an organ 

 with an important internal secretion, the tumor cells in many cases 

 produce the same internal secretion, which seems to have the same 

 functional properties as the normally produced' secretion. Thus a 

 metastatic growth from a thyroid tumor has been said to functionate 

 in place of the resected gland ; Gierke ^* found in about 20 grams of 

 material from metastatic thyroid tissue in the vertebral column about 

 5 mg. of iodin, which was a trifle larger proportion than was present 

 in the thyroid itself. Carlson and Woelfel "'' found much iodin in 

 the metastases of a thyroid carcinoma of a dog, while in another dog 

 whose cancerous thyroid contained no iodin the secondary tumors 

 were also devoid of this element. ^Marine and Johnson '^ found that 



fin.Tour. Med. Research, inn.3 (0), :]r-,(\. 



■!0 Ihid., mOo (l.*?), .54.S. 



Ti.Toiir. Expor. Mod., 101.3 (18), 512. 



-2 Lancet. 100.3 (ii), 224. 



73 .Tour. .Anat. and Phvsiol., 1804 (28). 142. 



74TTofrneisior's ■Reitr.."l0n2 (3), 280. 



-". Amer. Jour. Plivsiol.. 1010 (20), 32. 



70 Arch. Int. Med." 1013 (11), 288. 



