STUDIES IN THE GENUS GYMNOSPOR- 

 ANGIUM— III. THE ORIGIN OF 

 THE TELEUTOSPORE 



B. 0. Dodge 

 (With Plates 9-1 1) 



The manner in which the teleutospores are formed in the rusts 

 has been described by a number of authors, but our knowledge 

 of the origin and development of the teleutospore in Gymnos- 

 porangium is based mainly on the work of Sappin-TroufTy, 1 

 Blackman, 2 and Reed and Crabill. 3 Blackman makes the follow- 

 ing statement regarding the origin of the -spores in G. clavariae- 

 forme: "The teleutospores of this form are not borne on the 

 mycelium but arise from comparatively rectangular cells which 

 form a close-set layer on the surface of the mycelium at the points 

 where the teleutospores are developed. . . . They are similar to 

 the teleutospore-bearing cells described by Sappin-TroufTy for 

 G. Sabinae. . . . Each of these cells gives origin to a number 

 (not more than three or four) of narrow outgrowths which de- 

 velop into the stalked two-celled teleutospores." 



Reed and Crabill find that in G. macro pus the teleutospore is 

 formed by the budding of the upper cell of the pseudoparen- 

 chyma. " A layer of erect rectangular cells arises from this my- 

 celial mass just beneath and perpendicular to the cortex. These 

 cells elongate and their tips take on gradually the characters of 

 the incipent teleutospores." 



Weimer 4 has studied spore development in G. macropus and 



1 Sappin-Trouffy, P. Recherches histologiques sur la famille des Uredinees. 

 La Botaniste 5: 59-244, /. 1-60. 1896. 



2 Blackman, V. H. On the fertilization, alternation of generations and gen- 

 eral cytology of the Uredineae. Ann. Bot. 18: 3 2 3~373- pi. 21-24. 1904. 



3 Reed, H. S., and Crabill, C. H. The cedar rust diseases caused by 

 Gymnosporangium juniperi-virginianae Schw. Virginia Agr. Exp. Sta. Tech. 

 Bull. 9: 1-106. /. 1-23. My 1915. 



4 Weimer, J. L. Three cedar rust fungi, their life histories and the dis- 

 eases they produce. Cornell Agr. Exp. Sta. Bull. 390: 509-549. /. 136-157. 

 My 1917. 



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