364 



Profs. Percy Frankland and Marshall Ward. 



consisting of much broken filaments and rodlets, instead of forming 

 long tresses. 



The culture exposed over water, however, never gave any colonies 

 at all : the spores were all killed. 



That the light-action on the spores does not depend for its effect 

 on a high temperature, however, follows not only from the previous 

 experiments, but also, and very clearly, from the following one, 

 carried out on July 1, a hot day with a cloudless blue sky, but some- 

 what hazy, probably owing to London smoke brought up the Thames 

 valley by the light east wind then prevailing. 



Spores were sown in 10 per cent, gelatine with traces only of broth 

 and glucose, all the arrangements as before. The sowings were made 

 and exposures started at the open south window at 9 A.M. The 

 following table summarises the results : 



At 3.30 several of the filaments under bichromate were measured, 

 and gave from 9 to 10 fi to 20 /t, and even greater lengths (one was 

 nearly 40 /t), whereas the most I could find in the culture over 

 water were a few doubtf al cases of commencing germination. 



At 5 P.M. the shortest of the filaments over bichromate were about 

 30 /u, and the longest 130 /t. Twelve measurements gave 30, 36, 30, 

 45, 54, 45, 90, 99, 76'5, 135, 67'5, and 67 /t respectively, whereas no 

 measurable filaments could be found in the culture over water, a few 

 doubtful rods of 4 or 5 fi alone occurring. 



Moreover, it was evident ihat the bichromate-culture filaments 

 were growing verv rapidly, and one was selected for observation, 

 with the following results : 



