376 RETROGRESSIVE CHANGES 



X=rays ^" stimulate cell growth when applied in small amounts,^^" 

 hut larger amounts produce necrosis, which is peculiar in that an in- 

 tem'al of several days, or even weeks, may elapse after the exposure 

 before the necrosis manifests itself. Ellis ^^^ considers that the amount 

 of necrosis is out of proportion to the changes in the vessels, which 

 some have believed to be the cause of a--ray gangrene, and therefore 

 that the cells must be directly injured,^" a view supported by Cascr 

 mir's^^ experiments with plant cells. The extensive studies of the 

 Hertwigs show that the chromatin is chiefly affected, which presum- 

 ably explains the fact that immature cells, and cells in active division, 

 are more sensitive to ic-rays than adult cells, and that monstrosities 

 develop from eggs exposed to radiant energy. As far as histological 

 changes show, hard rays produce less but quite the same changes as 

 soft rays. That .r-rays have a marked effect on metabolism has been 

 abundantly established.^* According to ]\Iusser and Edsall,^^ the ef- 

 fect of ar-rays upon metabolism is unequalled by any other therapeu- 

 tic agent, and is manifested by excessive elimination of the products 

 of protein destruction, which arise particularly from the lymphatic 

 structures." These changes have been studied, therefore, particu- 

 larly in connection with the treatment of leukemia (q. v.). In con- 

 sequence of the injuiy to the blood-forming tissues, resistance to bac- 

 teria is decreased (Lawen).*^ The renal epithelium seems also to 

 suffer injury in some cases.*- 



Badiiun, which shares with x-rays the power of causing tissue 

 necrosis, does not have a similar effect upon the blood, nor do the 

 ultra-violet rays (Linser and Helber).^^ In general, however, radium 

 has much the same effect on tissues as .r-rays,** but seems rather to 



35 Full review by Cohvell and Russ, "Radium, X-Rays and tlio Living; Cell," 

 London, 1915. Also see Richards. Science, 1915 (42), 287. 



3oaSee Schwarz, Miinch. med. Woch., 1913 (60), 21G5. 

 3-.b Amer. -Tour. :\red. Sci., 190.3 (125). 85. 



36 Allen (Jour. :Med. Research, 1903 (9), 402) states that i)rotnzoa and vinegar 

 eels are killed by long exposure to ir-rays, wheieas plants are decidedly stimulated 

 in their growth. 



37 Med.-Xaturw. Arch., 1910 (2). 423; r^sum^ on iP-rays. 



■'■^ See Harvey (Jour. Path, and Bact., 1908 (12), 548)', concerning the effects of 

 a;-rays. 



3o'Univ. Penn. Med. Bull., 1905 (IS), 174: also Edsall and Pemberton. Amer. 

 Jour. Med. Sci., 1907 (133), 426. 



•«o A peculiar selective action for the generative cells is also shown by .r-rays, 

 which cause marked atrophy of the ovaries and testicles. In the latter it aflVcts 

 chiefly the gerniinative cells, spari'i' Mic cells of Levdig. (See Albers-Schonbcrg, 

 Miinch. med. Woch., 1903 (50), 185'): Frieben, ihid.. 1903 (50), 2295; Spccht. 

 Arch. f. Gvn.. 1906 (78), 458; Tlialer. Deut. Zeit. f. Chir., 1905 (79), 576; Rcif- 

 ferscheid, Zeit. f. Cvn., 1910 (34), 593. 



■ti Mitt. Grenz. Med. u. Chir., 1908 (19), 141. 



42 See Schulz and Hoffman, Deut. Zeit. f. Chir., 1905 (79), 350: Warthin, Amer. 

 Jour. :Med. Sci.. 1907 (133), 736. 



■•3 Deut. Arch. klin. Med., 1905 (S3), 479. 



44 Review bv Cuvot, Cent. allg. Path., 1909 (20), 243; also see :Mills. Lancet. 

 1910 (179), 462; Ricliards, Science, 1915 (42), 287. 



