LIGHT THERAPY MAYEE 395 



FURTHER PHYSIOLOGIC EFFECTS OF LIGHT 



The increase in calcium and phosphorus content of the blood 

 serum in rickets and tetany under ultra-violet radiation is due in 

 all probability to an increased absorption of calcium from the intes- 

 tine.^" 



Antirachitic or calcium-depositing agents, namely, vitamin D and 

 ultra-violet rays of sunlight and of artificial sources, increase the 

 free acid of the gastric contents, resulting in an increase in duodenal 

 acidity. This aids in holding calcium salts in solution with the con- 

 sequent increase in calcium absorption. Also, phosphorus absorp- 

 tion is increased, since calcium is usually associated in the body with 

 phosphorus in the form of phosphates. Sometimes phosphorus 

 absorption may be the primary effect. 



Under solar radiation, the blood shows increased alkalinity, a fact 

 attributed more to the action of the heat rays.^^ 



Radiation with massive exposures from carbon and mercury arcs 

 has increased persistently red blood cells and reticulocytes,^- but, 

 contrary to expectation, there was no great influence exerted in 

 hemoglobin regeneration in severe secondary anemia produced by 

 continual bleeding of animals. Increase of hemoglobin in human 

 anemias has been reported. However, this work does not yet con- 

 vince us without much further support that such radiation is bene- 

 ficial clinically in cases of anemia. 



Eeticulocytes vary in number with the season, being highest in 

 the spring and lowest in the winter. This seasonal variation seems 

 to be in direct proportion to the amount of sunshine. There may 

 be a relation between the cure and the prevention of anemia, and 

 sunlight or ultra-violet.^^ It is interesting to note that Macht found 

 the serum of an individual suffering from pernicious anemia toxic 

 to plant seedlings, this property being absent in specimens of blood 

 from those with secondary anemia or other blood diseases. When 

 the serum of a patient with pernicious anemia is irradiated with 

 ultra-violet, it becomes much less toxic. These observations are in 

 accord with those of some workers of a particularly favorable re- 

 sponse of some patients with pernicious anemia to artificial sources 

 of light. 



Lymphocytosis in rabbits and possibly in man can be produced 

 by exposure to the shorter ultra-violet rays.^* Hematoporphyrin 



*> Abrahmson, E. M., and Miller, E. G., Proc. Soc. Bxper. Biol, and Med., vol. 22, p. 438, 

 1925. 



^ See footnote 26. 



'"Laurens, Henry, and M.iyerson, H. S., Jonrn. Nutrition, vol. 3, p. 465, March, 1931. 



«* Macht, D. I., and Anderson, W. T., jr. Journ. Pharmacol, and Exper. Therap. vol. 84, 

 p. 365, December, 1928. 



^ Clarlf, Janet H., Amer. Journ. Hyg., vol. 1, p. 39, January, 1921. Hardy, M., and 

 Chapman, J., Amer. Journ. Ilyg., vol. 10, p. 655, November, 1929. Spence, K., and Grif- 

 fith, H. D., Report of the Medical Officer of the City of Aberdeen, p. 48, 1927. 



