374 h'i:Tii'(Kih'i:ssni-: ciiAyaEH 



ing depends not so mueli u])()n the freezing of the cells themselves as 

 upon the formation of hyalin thrombi in the injured vessels (v. 

 Recklinghausen, Hodara).-^ Kriege -- found that if the freezing is 

 transitory, the thrombi may again disappear; if over two hours in 

 duration, tliey are persistent. Rischpler,-' however, considers that 

 cell death is due primaril}- to the eft'ect of the cold upon the cells. On 

 tlie other hand, Stechelmacher -^^ found that freezing of liver tissue 

 produced the same changes as ligation of the hepatic artery, i. e., in- 

 creased permeability of the cell wall followed by similar changes in 

 the nucleus, suggesting that the changes produced by freezing depend 

 on the vascular changes. 



Light.-"' — Light may atfect tissues seriously, apart from the efifects 

 of accompanying heat, although the experiments of xVron -^ indicate 

 that insolation does not depend on the light rays, but solely on the 

 heat. Tn the treatment of lupus by the Finsen method with concen- 

 trated light rays, the action is largely a stimulating one, but associ- 

 ated with or subsequent to a certain degree of cell injury. Ogneff -'' 

 found that moderate action of electric light, rich in violet and ultra- 

 violet rays, causes mitotic cell division : if the action is stronger, the 

 cells undergo amitotic division and then become necrotic. Blue rays 

 have but slight cytotoxic action, and rays further towards the red end 

 of the spectrum are without demonstrable effect. Light l)aths are said 

 by Oerum -•' to increase greatly the quantity of corpuscles and hemo- 

 globin, while residence in the dark reduces these elements. The de- 

 struction of bacteria by light is a well-known phenomenon,-" but it 

 has been suggested that their destruction depends rather upon the 

 action of substances produced in the culture-medium under the influ- 

 ence of light than upon the effect of the light ujion the bacterial cells 

 themselves. In view of the fact that enzymes and antibodies in solu- 

 tion are quite readily weakened or destroyed by the action of light, it 

 is possible that intracellular enzymes may be similarly destroyed by 

 light, with resulting cell death. However, in the case of bacteria, at 

 least, the effects of light seem to depend upon oxidation processes, for 

 in the absence of oxygen, bacteria are not seriously injured by light, 

 and D'Arcy and TIardy -* fouiul that "active oxygen" is formed by 

 the same ])()rtion of tlie sjiectrum that is most active in destroying 



21 Miinch. med. Woch., 1896 (43), 341. 



22Virc'how's Arch., 1880 (11(5), f>4. 



23Ziefrl('r's Beitr., 1900 (2S), .541. 



23aBoitr. path. Anat., 1913 (57), 314. 



23bT{ovi(nv l)y Bering', Er<ieb. alljr. Pathol.. 1914, Aht. 1. (17). 790. Soo dis- 

 cussion of the principles of the action of lij^ht on tissues h\' Hox if, Anicr. .lour. 

 Tro])ical Dis., 191. I (2). 500. 



2t I'liilippine .Tour. Sci., B, 1911 (G). 101. 



2r. I'lliijrer's Arcli., 1890 (03), 209. 



2<i Plliifrer's Arch.. 190(1 (114), 1. 



27 Literature fjrivcn by WiesiuT, .\rch. f. llvg.. 1907 Mil). 1. 



2x.l<)iir. of I'liysiol.. 'lS!l.-> (17). 390. 



