E. S. Salmon 305 



Group II. — Outside — later moved into greenhouse. 



Class a. OR 38 (6); OR 39 (7); V 91 (1); V 93 (1); Z 42 (1);Z2(1);Z 14(1); OD 19 

 (2); HH 44 (1); OB 34 (10). "Golden Hop" (from Messrs Bide (6), from Messrs 

 Bunyard (2)). 



Class b. 0C6(1). 



Group III. — Outside^ater moved into hop-garden. 



Glass a. OR 38 (11); OR 39 (8); Z 25 (3); V 91 (1); V 92 (1); V 93 (1); Z 42 (2); 



Z2(2): Z 14(2); OD19(3); Z22 (2); HH44(2); OA49(2); OB 34(10); Z 17 (1); 



Z 31 (1). "'Golden Hop" (from Messrs Bide (8), from Messrs Bunyard (2)). 

 Class b. Z 15 (2); OC 6 (2); OA 33 (2); Z 23 (2); OD 17 (1). 

 Class c. OA36(l); Z39(l); OA 35 (1); OA 26 (1); II 31 (1); OB 48(1); OD 16(1); 



Z24(l); Z26(l). 



The plants in Group I behaved as follows : 



Class a. All the plants remained persistently immune. 

 Class b. All the plants proved "semi-immune" (see p. 302). 



Class c. All the plants quickly became fully infected, OA 26, Z 39, and II 31 being 

 noted as becoming virulently infected. 



The plants in Groups 11 and III were examined on June 13th, up 

 to which date they had stood together in the open outside the greenhouse ; 

 all the plants in Class a of both Groups were healthy; of those in Class 6, 

 one plant of OA 33 showed in a typical form the phenomenon of "semi- 

 immunity," and on one plant of OD 17 there was a very minute " powdery" 

 patch on two of the leaves; the remaining plants were healthy. In 

 Class c, more or less numerous, small patches of mildew (from natural 

 infection) occurred on all the plants, with the exception of OA 36. 



The plants of Groups II and III were then placed, respectively, in 

 the greenhouse or in the hop-garden. 



In the greenhouse the plants of Group II, Class (t remained as per- 

 sistently immune as those of Group I, Class a. The experiment shows, 

 then, that the immunity of such seedlings as these is not dependent on 

 the plants having been raised under greenhouse conditions, but is main- 

 tained when plants with shoots 2-3 ft. high produced in the open are 

 taken into the greenhouse. Similarly, the seedling OC 6 in Group II. 

 Class 6 showed the phenomenon of "semi-immunity" when taken into 

 the greenhouse and inoculated. 



With regard to the plants of Group III, no mildew was noticed on 

 the plants in Class a u]) to the end of September. The frosts which 

 occurred early in October shrivelled up the leaves of many of the plants, 

 but on October 23, when an examination was made of all the plants still 

 possessing young green leaves, one plant of OR 38 was found to be 



