14 



Scientific Proceedings (125) 



creased respiration 300 per cent. An hydrogen atmosphere (no 

 precautions were taken to free the gas from traces of oxygen 

 and C0 2 ) reduced respiration to 50 per cent. Reducing the 

 atmospheric pressure 5-10 per cent, has no appreciable effect 

 on respiration, while increasing the pressure 10 per cent, has a 

 stimulating effect. 



The ratio between the sulfur oxidized and carbon assimilated 

 by the culture is about 32, this ratio varying greatly by chang- 

 ing the conditions of growth and by adding various depressive 

 substances. The presence of nitrates, for example, greatly in- 

 creases the ratio. When thiosulfate is used as a source of energy 

 the ratio is about 65. Of the total amount of energy made avail- 

 able only about 6.5 per cent, is utilized by the organism. The 

 amount of energy utilized by the nitrite and nitrate bacteria is 

 about 5 per cent. These quantities in comparison with the low 

 utilization of energy by higher plants point to the greater ef- 

 ficiency of the autotrophic bacteria. 



4 (1964) 



A study of light waves in relation to their protective action in 



rickets 



By ALFRED F. HESS, A. M. PAPPENHEIMER and M. WEINSTOCK. 



[From the Department of Pathology, College of Physicians and 

 Surgeons, Columbia University, New York City] 



In a communication presented a year ago we showed that 

 rickets can be prevented in rats by daily exposures to direct sun- 

 light for about fifteen minutes 1 . A similar result was reported 

 at the same time by others 2 . When rats were placed in a box 

 having flint glass windows it was found that the sun's rays, in 

 traversing the glass, had lost their protective power. In a later 

 communication it was shown that the pigment of the skin also 

 hinders the action of the effective rays, that black rats require 

 more radiation than do white rats 3 . 



1 Hess, A. P., Unger, L. J., Pappenheimer, A. M., Proc. Soc. Exp. Biol, 

 and Med., 1921, xix, 8. 



2 Shipley, P. G., Park, E. A., Powers, G. F., McCollum, E. V., Proc. Soc. 

 Exp. Biol, and Med., 1921, xix, 43. 



3 Hess, A. F., Unger, L. J., Pappenheimer, A. M., Proc. Soc. Exp. Biol, 

 and Med., 1922, xix, 238. 



