﻿i 9 i6] BOVIE— SCHUMANN RAYS 27 



to go too far, but merely stimulates it if stopped at the right time. 



It is interesting to note that the photolyses previously described 

 follow the photo-chemical-energy law first formulated by Talbot, 

 that the amount of chemical change is proportional to the product 

 of the intensity times the length of exposure, or, if the intensity is 

 constant, that the amount of chemical change is proportional to the 

 length of exposure. It required the same total length of exposure 

 to bring about cytolysis when the illumination was interrupted as 

 when it was continuous. 



In the Schumann region of the spectrum, as in the regions of 

 longer wave length, the destructive action of the light increases as 

 the wave length decreases, and when we consider the very short 

 exposure which was required for killing, notwithstanding the feeble 

 source of light used, it is evident that the light of the Schumann 

 region is much more destructive than the light of the regions of 

 longer wave length. In other words, the curve representing the 

 relation between wave length and destructive action, which slopes 

 upward in the regions of shorter wave lengths, continues into the 

 Schumann region of the spectrum without changing its character. 



Laboratory of Plant Physiology 

 Harvard University 



LITERATURE CITED 



1. Bang, Uber die Verteilung bakterientdtender Strahlen im Spektrum des 

 Kohlenbogenlichtes. Mit. Fin. Med. Lichtinst. 9: 164. 1005. 



2. Barlow, On the exclusion of light in the treatment of smallpox. Lancet. 

 1871. 



3- Bus, Finsen's Phototherapy. Phila. Med. Jour. 1899. 



4- , Finsen's Phototherapie. Die Medicinische Woche. 1900. 



5- , Finsen's Phototherapie. Therapeutische Monatshefte. 1000. 



6 - — , Professor N. R. Finsen's Lichttherapie. Zeitsch. Elektrotherapie 



und Arztliche Elektrotechnik. 1899. 



7- , Remarks on Finsen's Phototherapy. British Med. Jour. Sept. 30. 



1899. 



8. Bovie, The temperature coefficient of the coagulation caused by ultra- 

 violet light. Science N.S. 37:373. 1013. 



9- Charcot, Erytheme produit par Faction de la iumiere electrique. Compt. 

 Rend. 10:63. 1858. 



io. Downes and Blunt, Researches on the effect of light upon bacteria and 

 other organisms. Proc. Roy. Soc. London 26:488. 1877. 



