380 



Profs. Percy Frankland and Marshall Ward. 



Temperatures. 



12.40 P.M., 



12.50 , 



1.0 , 



2.0 , 



2.15 , 



3.0 , 

 4.0 



Blue cell. 



12-75 



10-8 



10-4 



9-9 



9-5 



8-5 



7-0 



Eed cell. 



12-0 



10-75 



10-3 



9-9 



9-5 



8-5 



7-0 



At 4 P.M. the cultures were brought into the laboratory, where the 

 temperature rose to 12'5 C., and there is no question as to the tem- 

 perature being identical in both cells from 2 P.M. onwards, and at no 

 time after the first ten minutes of exposure did the temperature 

 differ by more than -^th of a degree C. 



When the cultures were first put out the spores were swollen, and 

 were already beginning to germinate, and if they had remained at 

 22 C. till 4 P.M. they would have developed filaments from 90 to 150 /t 

 long, as shown by two sister cultures left at 22 C. as controls, and 

 which were examined at 4 P.M. 



As it was, the exposure to a low temperature 12 to 7 C. of 

 course checked both cultures. 



Nevertheless, at 6 P.M. the red culture showed several rodlets 

 9 to 10 ft. long, one 6 /*, and two or three 4'5 to 5 /t, whereas I could 

 discover plenty of swollen and germinated spores 2 3 /tt long, and 

 even one rodlet 4'5 /t long in the blue, but nothing longer. The 

 following table gives the successive measurements. 



It will be seen that here we have obvious retardation by 3-| hours of 

 diffuse blue light acting on the young rodlets, and that this retarda- 

 tion was entirely independent of the temperature, which was the 

 same in both cases. (See Curves 74 and 75.) 



* The mean is raised by a single filament which was (81 p), much longer than 

 any others. 



