i888.] 



NEW-YORK MICROSCOPICAL SOCIETY. 



85 



THE FUNGUS, PHRAGMIDIUM MUCRONATUM, LK., 

 VAR. AMERICANUM, PECK, THE ROSE BRAND. 



BY THE REV. J. L. ZABRISKIE. 

 A Description of Exhibit No. i, of the Programme of November ^th, 1887.) 



This Fungus infests both surfaces of living leaves of the cul- 

 tivated Rose. It has two forms of fruit : (i) the earlier Uredo- 

 spores, which are unicellular, sub-oval, and of bright orange 

 color ; (2) these later Brand-spores, which 

 are dark brown, five to nine septate, ter- 

 minal joint mucronate ; the compound 

 spore being supported on a lengthened 

 peduncle, which is hyaline, fusiform and 

 ^3 incrassated below. 



Our State Botanist, Prof. C. H. Peck, 

 says, "American specimens generally have 

 the spores more opaque, and with two or 

 three more septa than the typical form. 

 g \ This variant form might be called, var. 



Americanum." (28th Rep., p. 86.) 



The specimen here exhibited has an 

 ^j ^ eight-celled spore, with a nucleus visible 



X 250, i^ each cell, notwithstanding the dark color 



Phragmidium Mucronatura, of the cell-walls. 

 Lk., Var. Americanum, 



Peck. The specimen may perhaps be inter- 



esting from the fact that it was mounted in glycerine, and sealed 

 with white-zinc cement on March 17, 1880, more than seven and 

 a half years ago, and still seems to be in perfect condition. 



