﻿Dodge: Effect of host on Gymnosporangium 533 



material of G. hiseptatum was brought into the greenhouse. 

 It requires three or four weeks after aecidia make their first 

 appearance on Amelanchier for them to reach their full length. 

 Some of them appear to be unable to force their way out of the 

 gall readily. The peridial cells loosen up so that spores are 

 scattered long before the full growth of the peridium is attained 

 (Fig. 24). 



A large quantity of G. hiseptatum was obtained at Lakehurst, 

 New Jersey, on April 25, 1915. G. fraternum was not as abundant 

 here as at Newfield, although scattering infections could be found 

 on almost any Chamaecyparis . 



Another set of cultures on Aronia and Amelanchier was made 

 with G. fraternum from this locality. A summary of the results 

 is given in Table IV. 



TABLE IV 

 Gymnosporangium fraternum from Lakehurst in 



Only a small supply of teleutospores was available May 3 and 

 May 16. This in part accounts for the low percentage of infec- 

 tion on these dates. The Aronia leaves were rather old to expect 

 good results. Three-fourths of the Aronias were infected and 

 most of them developed a large number of aecidia. Four out of 

 seven Amelanchiers were also infected. While Amelanchier 

 Amelanchier was infected none of the plants of this species matured 



The question of determining whether the caulicolous form 



