INTERNAL SECRETION 417 



that tumor cells resemble all other cells in possessing intra- 

 cellular proteolytic enzymes. We have no evidence that these 

 enzymes are different, either qualitatively or quantitatively, 

 from those of corresponding normal tissues. They are dis- 

 cussed more fully under the subject of autolysis (Chap. iii). 

 The influence of radium rays in hastening autolysis of cancers 

 is even greater than that of x-rays (Neuberg *). 



Other enzymes are also present in tumor cells. Buxton 2 

 examined a large number of tumors for their enzymes by the 

 plate (auxanographic) method, and found considerable varia- 

 tions in different growths. All contained amylase (splitting 

 starch) and lipase (splitting butyrin). Most, but not all, 

 tumors coagulated milk and liquefied casein, and also liquefied 

 gelatin (rennin, proteases). Peroxidase was nearly always, 

 and catalase always, present. Digestion of fibrin, coagulated 

 serum, and coagulated egg-albumen could not be observed. 

 Practically all tumors split glycogen. Tyrosinase could not be 

 demonstrated. The fact that early embryonic tissues were 

 found poor in enzymes 3 speaks against the common assumption 

 that tumors represent strictly an embryonic formation. 



MacFadyen and Harden 4 studied the juices obtained by 

 grinding up tumor cells made brittle by liquid air, and found 

 by direct methods (chiefly in breast cancers) invertase, maltase, 

 amylase, proteases acting in both acid and alkaline solutions, 

 catalase, oxidase, with perhaps traces of lipase and peroxidase, 

 but no lactase. 



Tumors arising from the gastric mucosa, according to War- 

 ing, 5 contain both pepsin and rennin ; those from the pancreas, 

 both primary 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 known to functionate in place of the resected gland ; 

 Gierke 6 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 



1 Arb. a. d. Path. Inst. zu Berlin, 1906, p. 593. 



2 Jour. Med. Eesearch, 1903 (9), 356. 

 8 Ibid., 1905 (13), 543. 



4 Lancet, 1903 (ii), 224. 



5 Jour. Anat. and Physiol., 1894 (28), 142. 



6 Hofmeister's Beitr., 1902 (3), 286. 



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