Diseases of the Rose. 



125 



which float in the air and impregnate healthy tissues. 

 See Fig. 32. 



Fig. 31. 



The reason why some varieties are more liable to its 

 ravages than others, is not easy of explanation. That 

 it is oftener present in teas containing an admixture of 

 hybrid blood is unquestioned, 

 and would seem to confirm the 

 theory of some that it is engen- 

 dered by such crosses. I am 

 more inclined to think it is 

 transmitted, and that for some 

 reason unknown to us, the cross 

 is much more subject to it than is the parent hybrid. 

 It is rarely seen in a true tea- rose unless it has been 

 subjected to contagious influences, while many of the 

 hybrids cannot be grown in the open air on account of 

 its ravages. 



Of the many hybrid teas which have appeared within 

 the last ten years and have been given a trial, none re- 



Fig. 32. 



