Dodge: The Genus Gymnosporangium 183 



G. glob o sum and apparently agrees with Reed and Crabill regard- 

 ing the first species. " From these stromatic layers the telispore 

 stalks arise." Of G. globosum he says : " The telial horns are de- 

 veloped from a stromatic layer in the same manner as are those 

 of G. juniperi-virginianae." Weimer's figure 156 shows a ma- 

 ture sorus of G. clavipes. At the margin teleutospores are figured 

 arising directly from the outermost cells of the pseudoparen- 

 chyma. 



If we use the term basal cell in the usual sense, that is, to 

 designate the cell from which various spore forms take their 

 origin, then, according to the authors cited above, the basal cell 

 in the teleutospore sorus is the upper or terminal cell of the 

 pseudoparenchyma or stromatic mass. The writer 5 has recently 

 described the origin of the teleutospore in G. transformans and 

 G. fraternum and has since studied this question in G. macropus, 

 G. globosum, G. clavariae forme and G. nidus-avis. In all of 

 these species at least the true basal cell is not the upper cell in 

 the chain but it is the penultimate cell from which the teleu- 

 tospore arises by budding. In G. transformans and G. fraternum 

 the upper cells increase in size considerably, lose their cytoplasm 

 and nuclei by degeneration, and become mere bladdery sacs sev- 

 eral times their original length, so that the epidermis is raised 

 further and finally broken open. The penultimate cell then grows 

 out through or between the buffer cells, forming a narrow bud 

 from which the teleutospore is formed by further growth. In 

 G. transformans the buds seem to grow up very quickly so that 

 the formation and degeneration of the terminal cells may be over- 

 looked. In G. fraternum, however, the buffer cells form a strik- 

 ing palisade layer which frequently extends clear across the sorus 

 primordium. 



Material and Methods 



Some of the material used in these studies was obtained from 

 plants artificially infected in the greenhouse. In most of the work 

 material from naturally infected plants was also studied. It has 



5 Dodge, B. O. Studies in the genus Gynosporangium — I. Notes on the 

 distribution of the mycelium, buffer cells and the germination of the aecidio- 

 spore. Brooklyn Bot. Gard. Mem. i : 128-140, pi. 1 X f. 1-5. My 1918. 



