504 THE CHEMISTRY OF TUMORS 



in cancer, benign tumors and normal cells, except that sometimes in 

 cancer they fix stains less firmly (^Goodpasture). ^^ 



There has been some effort to correlate the cholesterol and lecithin 

 contents of blood and tissues with the rate of cancer growth; apparent- 

 ly lecithin inhibits growth and cholesterol stimulates.^'' However, 

 Bullock and Cramer" found much more cholesterol in a slowly growing 

 mouse carcinoma than in a rapidly growing one, somewhat more phos- 

 phatid in the latter, much more phosphatid in a sarcoma than 

 in the carcinoma, and cerebrosides only in the latter; in necrotic 

 portions of tumors they found an increase in simple fats. These 

 figures are based on too few observations to be interpreted as yet. 



(3) Inorganic Constituents. — These have been studied by Clowes 

 and Frisbie^*^ under exceptionably favorable conditions, in that the age 

 of the tumor could be accurately estimated, in the inoculable carcinoma 

 of mice. They found that rapidly growing tumors contain a high 

 percentage of potassium and little or no calcium, whereas in old, 

 slowly growing, relatively necrobiotic tumors the relation is reversed, 

 the potassium decreasing greatly while the calcium increases. Mag- 

 nesium is present only in traces, while the proportion of sodium fluc- 

 tuates much less, but is usually greater than either the potassium or 

 calcium, although in very old tumors the latter may become excessive. 

 The most rapid growth, however, seems to occur in tumors in which 

 both calcium and potassium are present in the ratio of 



K 2 3 

 Ca = l°^'2 



Beebe^^ analyzed a number of human tumors with the following 

 results: Phosphorus was found in proportion to the amount of nu- 

 clear material, varying from 0.139 per cent, (uterine fibroid) to 1.06 

 per cent, (sarcoma). Iron varied from 0.013 per cent, to 0.064 per 

 cent., probably depending on the amount of blood and nucleoproteins. 

 Calcium is most abundant in old degenerated tumors, and potassium 

 in rapidly growing tumors. These results, supported by Clowes and 

 Frisbie's findings, indicate the importance of potassium for cell growth. 

 Injection of potassium salts into mice increases their susceptibility 

 to inoculation (Clowes),^^ while calcium decreases cancer growth 

 (^Goldzieher).^^ Exposure of isolated cancer cells to calcium salts 

 reduces their growth capacity when inoculated, apparently through 

 reducing their water content; both effects arc counteracted by sodium 



" Jour. Med. Res., 1918 (38), 213. 



" See Robertson and Burnett, Jour. Exp. Med., 1913 (17), 3-14; 1016 (23), 

 631; Sweet et al, Jour. Biol. Chem., 1915 (21,, 309; Luden, Jour. Lab. Clin. Med., 

 vols. 3 and 4. 



^f- Proc. Royal Soc. London (B), 1914 (87), 230. 



•■sAmer. Jour. Phvsiol., 190.5 (14), 173. 



" Amor. Jour. Pliysiol., 1904 (12), 167. 



" British Med. Jour., Doc. 1, 1906. 



6" Vorhandl. Dout. Path. Gesellsch., 1912 (15), 283. 



