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BROOKLYN BOTANIC GARDEN MEMOIRS 



the rust. The difference in the shape of the buffer cells of G. trans- 

 formans and G. jraternum corresponds roughly with that between the 

 teleutospores ; they are comparatively long in the latter species. 



On January 30, 1917 a potted plant naturally infected with G. 

 fraternum was taken from the cold frame and examined. Several 

 leaves showed by the presence of slight yellowish spots that they 

 would develop sori. Sections of one leaf cut on this date showed 



Fig. 4. Section of a leaf of the white cedar infected with G. jralernum show- 

 ing the layer of buffer cells at the time when the epidermis has been quite completely 

 disorganized. At the right a large palisade cell in the process of disorganization, 

 but the nucleus is still visible and a haustorium is present. 



that the pseudo-parenchyma or teleutospore primordium was well 

 marked. The buffer cells were mostly without granular contents and 

 nuclei (Text-fig. ^, A). In a few cases fragments of the degenerated 

 nuclei could be seen. By February 2, a sorus taken from the leaf of 

 the same plant showed great numbers of teleutospore buds in the 

 2- and 4-nucleated stages (Text-fig. 5, C). A few buds had 6 nuclei, 

 and the stalk cells of these had been cut ofif. Buffer-cell walls 

 were just visible as narrow irregular lines showing most distinctly 

 at the base of the young teleutospore. Two days later, February 4, 

 cross-walls had been formed in many spores but nuclear fusion had 



