284 JXFLAMMATIOX, REGENERATION, GROWTH 



tiou in response to chemical stimuli might be cited, but in nearly all 

 cases it is extremely difficult to determine that the proliferation is 

 not, after all, reparative in compensation for degenerative changes, 

 and, therefore, possibly obeying some other biological law than that 

 of a simple reaction to a chemical stimulus. 



Although proper nutrition is necessary for cell proliferation, yet it 

 does not seem that excessive nourishment can lead to excessive cell mul- 

 tiplication, or by itself cause cell proliferation to take place. Oxygen 

 and certain inorganic salts are essential for cell division even in the 

 lowest forms, and among such simple organisms as sea-urchins and 

 certain other marine forms segmentation of the unfertilized ova may 

 be incited by changes in osmotic concentration, leading eventualh* to 

 formation of perfect larvje (J. Loeb, et. al.).^^ In lower animals 

 verj' dilute solutions of alkalies stimulate the rate of cell growth, and 

 somewhat higher concentrations cause extremely irregular cell division ; 

 in mammals the feeding of alkalies causes great wasting as if through 

 cell stimulation.^ The products of nuclein hydrolysis are said to 

 stimulate cell growth.- Potassium salts seem to be particularly im- 

 portant for proliferating cells, and Beebe and also Clowes and Fris- 

 bie ^ have found that actively growing malignant tumors are rich 

 in potassium and poor in calcium, whereas in slow-growing tumors 

 the reverse is the case. Dennstedt and Rumpf * also found that in 

 hypertrophy of the heart the amount of potassium is increased, while 

 in chronic degeneration of the myocardium the calcium and mag- 

 nesium are usually increased. The proportion of nitrogen in the dif- 

 ferent parts of the heart is not changed during hypertrophy (Benee),^ 

 but the amount of NaCl is much increased in hypertrophy." 



Chemical studies of proliferation are lacking, except in regard to 

 the development of the embryo, etc."'"^ New tissues difiPer from adult 

 tissues in having a large proportion of water, and in having a larger 

 proportion of the "primary" cell constituents and a smaller propor- 

 tion of the various secondary constituents, since these last are largely 

 products of the activity of the adult cell. Of the primaiy constitu- 

 ents, the proportion of the nucleoproteins is particularly high, and a 

 number of interesting facts concerning the nucleoproteins in cell di- 

 vision have been determined. IMost important, perhaps, are the clas- 

 sical observation of INIiescher, who found that during the migration 

 of salmon up stream to the spawning grounds, during which time no 

 food is taken, the proteins of the muscular tissue become largely 



08 Sep J. Loob, Studios in Conoral Plivsiolofrv, Chioapo. 1005. 



1 Moore et al., Rioolicm. Jour.. 1900 h), 2\H: 1012 (6), 162. 



2 Calkins et al.. Jour. Infect. Di.s., 1912 (10), 421. 

 8 See "Tumors," Cliap. xvii. 



4Zeit. klin. Med., 190.5 (58). 84. 

 BZeit. klin. Med.. 1908 (06). 441. 

 « Rzentkowski, ihid., 1910 (70), 3.37. 



"a. l.iterature on the ehemistry of firowtli piven liy Aron, llandliueli d. Bioeliem., 

 Ergiinzungsband, 1913. 



