94 



coiled branches within the cells; only after about the tenth day 

 of an infection are these gradually replaced by intercellular 

 runners with haustoria. This is evidently a device to further 

 the quick establishment of the fungus in its host. (46) 



Another rust, Kuehneola alhida, infects the blackberry but 

 this one we find in the fall. We prize it then for we can get a 

 class exhibit as long as the reddened blackberry leaves hang on 

 the canes. Clover rust is also on the campus late in the fall. We 

 find it on both the white and the red clover. There is a nice 

 problem here in distinguishing the form-species of Uromyces 

 trifolii. (44) Snapdragons in the President's garden can usually 

 be depended upon to give us samples of rust until frost kills the 

 host. Snapdragon rust has reversed the usual course of emigra- 

 tion. It was reported in California in 1895 and by 1915 had 

 colonized New England both in greenhouses and in out-of-door 

 gardens. The rust perpetuates itself by means of the abundant 

 uredospores; its teleutospores apparently do not germinate. As 

 is the case with the carnation rust, teleutospores "are not a 

 necessity for a fungus the host of which occurs both under glass 

 and out of doors." (21) 



Several of the rusts on nati\'e plants take kindly to plant- 

 house culture. Chrysomyxa cassandrae was discovered in 

 mid-winter on a plant of leather-leaf which had been brought in 

 for forcing in a terrarium. Dandelion rosettes brought into the 

 planthouse bloom and fruit in the winter. We have even raised 

 a crop of seedling dandelion and have raised rust upon them: a 

 chance infection from a rusted rosette. The rust of Jack-in-the- 

 pulpit can be forced along with its host. The stage which bears 

 spermatia and aecidiospores is perennial in its host. It is wise 

 to locate the rusted plants in the woods when these spores cover 

 leaves and spathes in May if one would find the underground 

 corms for transplanting in the fall, for by that time the leaves 

 are dead and the late spores, the teleutopsores, are scattered in 

 the soil where the}' may infect new shoots as they push up in 

 the spring. We do not need this late stage for the planthouse; 

 we have only to dig the labelled corms and in February, in our 

 terrarium watch the rust pustules appear even before the Jack 

 leaves unfold. 



This adaptable rust seems an interesting plant rather than 

 a disease-producing fungus. \\'ithout attempting to minimize 



