374 Profs. Percy Frankland and Marshall Ward. 



After allowing the light, from the Hue sky only, to act on the 

 cultures for about 2 hours, the following measurements were made 

 of two filaments exactly the same length, as near as I could select 

 them : 



Bichromate. 



Here was evidence that the culture over water was growing less 

 rapidly than that over bichromate, but since the growth of the 

 filaments in the bichromate culture was rapidly approaching the long 

 lengths which I cannot measure, I determined to try the effect of 

 more direct insolation to see if the higher temperature and intensity 

 would bring more rapid action. Consequently I tried the results of 



