396 ANNUAL REPORT SMITHSONIAN INSTITUTION, 193 2 



injected subcutaneoiisly or applied locally to the mesentery of a frog 

 or a mouse sensitizes the vessels to the visible rays, capillary stasis 

 is produced, and thrombi of leukocytes are formed in the vessels at 

 different points along the endothelial wall, Eosin (1:1,000) sensi- 

 tizes the capillaries to the visible rays, so that stasis is produced by 

 these rays alone. Cell membranes and capillaries develop increased 

 permeability on exposure to ultra-violet rays. Animals kept in 

 darkness from birth can show growth changes differing in no way 

 from those exposed to light, but blood examinations have in some 

 experiments shown lowered blood platelets,^^ On exposure of these 

 animals to quartz mercury vapor arc radiations, the number of 

 platelets has rapidly increased to normal. There is also evidence 

 that the coagulation time is decreased. 



Basal metabolism is increased only slightly, if at all, by light ex- 

 posures alone, but it can be markedly increased by exposure to 

 moving air. Some workers have reported even a drop in many 

 cases. Increased heat output by radiation under a provoked hj'^per- 

 emia demands increased metabolism. Increased mineral metabolism 

 is definitely provoked by light alone to give increased urinary out- 

 put of nitrogen, phosphorus, sulphur and chlorides. Following ex- 

 posure to light, respiration is decreased in rate but increased in 

 depth. Increased body heat production obviously demands accel- 

 erated vital reactions. The rate of growth may be increased under 

 the action of light.^'' 



The improved physiologic action of the skin on exposure to light 

 may be presumed; namely, as to increased secretory and protective 

 powers. It may be speculated that the skin metabolism may be 

 stimulated by light and the formation of glutathione may be in- 

 creased. Perhaps the specific carbohydrate metabolism of the skin 

 which has been demonstrated experimentally by the presence of 

 lactic acid may likewise be stimulated.^" This conception of the 

 skin as an organ intimately concerned with complex chemical 

 processes presents increased importance to the possibilities of light 

 therapy. It has been related how intimately the skin is concerned 

 with the elaboration of lipoid substances and how the epithelium 



»= Gunn, F. D., Proc. Soc. Exper. Biol, and Med., vol. 24, p. 120, November, 1926. Sooy, 

 J. W., and Moise, T. S., Treatment of Idiopathic Purpura Hemorrhagica, Journ. Amer. 

 Med. Assoc, vol. 87, p. 94, July 10, 1926. 



3" Goldblatt, H., and Soaraes, K. M., The Effect of Radiation with the Mercury Vapor 

 Quartz Lamp on the Growth of Rats Fed on a Diet Deficient in the Fat-Soluble 

 Growth-Promoting Factor, Lancet, vol. 2, p. 1321, December 23, 1922. Hume, E. M., The 

 Effect of Radiation with the Mercury Vapor Quartz Lamp on the Growth of Rats Fed on 

 a Diet Deficient in Vitamin A, idem., p. 1318. Goodalo, H. D., Amer. Journ. Physiol., vol. 

 79, p. 44, December, 1926. Higgins, G. M., and Shcard, Charles, Journ. Exper. ZooL, 

 vol. 46, p. 333, 1926. 



5' Pillsbury, D. M., The Intrinsic Carbohydrate Metabolism of the Skin, Journ. Amer. 

 Med. Assoc, vol. 96, p. 426, Jan. 7, 1931. 



