892 THOMAS ORDWAY AND ARTHUR KNUDSON 



generation of cells resulting from influence of ultra-violet light rays are be- 

 lieved by Krebich to be caused by the proteins being rendered insoluble, 

 and as a consequence the catalase is more firmly bound and inhibited 

 in its action. Burge(rf) believes that ultra-violet radiation kills cells and 

 tissues by changing the protoplasm of the cells in such a way that certain 

 salts can combine with the protoplasm to form an insoluble compound or 

 coagulum. He found the effective region of spectrum to be from 0.254 H 

 to 0.330 [A. The action of the sun's rays on the non-pigmented skin of 

 animals is ascribed by Beijers to the action of the ultra-violet rays on sen- 

 sitizing substances which are present in the blood. 



The action of light on the blood of animals has been studied quite 

 extensively by Oerum(6). He found that the blood volume and the hemo- 

 globin are decreased in the dark. Red light has a similar effect but in 

 blue light a plethora is produced and hemoglobin is increased. Light baths 

 increase the blood volume in the course of four hours about twenty-five 

 per cent. The photodynamic action of light on blood has been reviewed 

 by Bering. By photodynamic action is meant the ability of certain fluores- 

 cent substances to produce in light strong biological action. The red blood 

 corpuscles are dissolved, some substances attacking the corpuscles within 

 the cell membrane, in others the primary attack is intercellular. Immune 

 serum loses its specificity. Polynuclear leucocytes and lymphocytes are 

 destroyed. The proteins of serum form a substance having a hemolytic 

 action. Traugott could observe no effect on the number of red blood 

 corpuscles in man following exposure to ultra-violet rays for ten to fifteen 

 minutes. An increase of leucocytes, however, was noted. Another effect 

 observed was that blood coagulated sooner and the number of blood plate- 

 lets was increased. Schanz(&) extended the observation of Chalupechy and 

 studied the effect of ultra-violet light on proteins in the blood and found 

 that after exposure of blood for eight hours there was a decrease in the 

 albumin from 27.0 mg. to 3.9 mg. per 100 c.c. of diluted serum and an 

 increase of globulin from 2.1 to 24.2 mg. per 100 c.c. Hausmann and 

 Mayerhofer noted that salted plasma exposed to ultra-violet light did 

 not coagulate when diluted with water, while untreated salted plasma co- 

 agulated in a few minutes. Likewise he observed that oxalated plasma 

 coagulated much more slowly after addition of calcium chlorid when 

 subject to the action of light. From these observations the authors em- 

 phasize the necessity of carefully adjusting the action of ultra-violet 

 light upon patients. 



The activity of most enzymes is found to be decreased after exposure 

 to light. Agulhon observed that ultra-violet rays may attack enzymes in 

 the absence of oxygen. Chauchard found that the activity of pancreatic 

 amylase is rapidly attacked by rays of wave lengths less than 2800 Ang- 

 strom units but not appreciably affected by rays of longer wave length. 

 Lipase was destroyed in part by rays equal to 3300 Angstrom units and 



