Erysiphe Polygoni. G. 0. Scarlc. 287 



The next series (D) carried on the fungus to the fourth genera- 

 tion on cut surfaces. 



Series D. Started Feb. 12th. Conidia from sources shown. 

 One inoculation in each case. 



No. of Source of 



Expt. conidia Host used Result Keniarks 



D I. C I "Cut M.S.K." Full Patches powdery 



infection with conidia. Very 

 distinct discoloura- 

 tion 

 D 2. C 3 ,, .. Medium Fairly numerous co- 



infection nidia. Very distinct 

 discolouration 

 D 3. C 4 ,, ,, Medium ,, ,, 



infection 



An attempt was made on March 6th to carry on to the hfth 

 generation on cut Marrow-stemmed Kale stem but the Kale was 

 by this time too old and all the pieces used soon died and rotted. 



However the above series show that it is possible to carry on 

 cultures of an Erysiphe on the exposed internal tissues of its 

 host over four generations in three months. 



An experiment was then tried to demonstrate whether in- 

 fection would take place on the internal tissue of the swollen 

 hypocotyl ("root") of the Swede in the same way as on the 

 stem of the Marrow-stemmed Kale. 



Series i S i. Started Jan. 28th. Conidia from sources shown. 

 One inoculation in each case. 



This series shows that infection took place quite successfully 

 on the internal tissue of Swede "root." In no case was there 

 any discolouration shown. 



An attempt was made to carry this series on to another 



M. s. 4 



