[Vol. 6 

 314 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



difference in size between both the oaeoma- and the teleutospores 

 of species from the two sources, but these points alone are not 

 sufficient to be considered as of specific importance. 



The characterization of the species is as follows: 



Melampsora Larici-populina Kleb. 



Aecidiospores. Caeomata hypophyllous, single or in groups, 

 with yellow spots on the upper surface, roundish or oblong, 

 1-1.5 mm, in diameter, orange-red, pulverous; spores roundish 

 or oval, finely and densely verrueulose, 22-37X18-27 p. 



Uredospores. Sori mostly hypophyllous, seated on yellow 

 spots, scattered over the whole surface, orange-yellow, pulverous; 

 spores oval or elongated, 26-40X16-22 pj membrane hyaline, 

 finely echinulate, without perceptible germ pore; paraphyses 

 capitate, with a slender pedicel, 16-22X55-80 p. 



Teleutospores. Sori epiphyllous, frequently hypophyllous, 

 dark reddish brown, scattered or in groups over the whole 

 surface, covered by the epidermis; spores cylindrical or some- 

 what wedge-shaped, 18-48X8-12 ju; membrane clear brown, 

 uniformly thin, without an evident germ pore; sporidia spheri- 

 cal. 



Caeomata on Larix leptolepis a ad Larix decidua; uredo- and 

 teleutospores on Populus balsamifera. 



Melampsora on Salix babylonica 



When negative results were obtained as to any relationship 

 between Caeoma on Chelidonium and Melampsora on Populus, 

 the author performed a new experiment by inoculating Cheli- 

 donium majus with teleutospore material obtained from several 

 species of Salix and Populus. 



As will be shown in the data of table ill, successful results were 

 only secured by sowing the teleutospore material obtained from 

 Salix babylonica. 



As may be easily seen, the species on Salix babylonica requires 

 Chelidonium majus for complete development of its entire life 

 cycle, but owing to the fact that no return infections to Salix sps. 

 have been made, the subject has not yet been completely estab- 

 lished. 



The aecidial stage resulting from the successful inoculation 





