THE BASIDIA OF PUCCINIA MALVACEARUM 533 



the germination of the teleutospores was not shown in connection 

 with the host-plant. I have therefore supplemented my researches 

 on the two species in question by an investigation on Puccinia 

 Malvacearum in wJiich I have sought to make clear the relations 

 of the basidia to the teleutospore-sorus upon the host-plant. A 

 detailed account of these investigations will now be given which will 

 serve to illustrate in a particular case the principles of organisation 

 for the production and liberation of the basidiospores of Uredineae 

 in general. 



The Shape and Position of the Basidia of Puccinia Malva- 

 cearum during Spore-discharge. — Puccinia Malvacearum is one of 

 the best-known of the Uredineae, largely because of its extremely 

 frequent occurrence on the Hollyhock {Althaea rosea) grown in 

 gardens. Taubenhaus ^ has contributed interesting facts concerning 

 its morphology and life-history, while Robinson ^ has written a 

 memoir on the relations of the fungus to the tissues of its host. 



The material for my observations was obtained at first from an 

 infected leaf of Malva sylvestris and subsequently from infected 

 leaves of the Hollyhock. Part of a leaf of a Hollyhock showing 

 numerous teleutospore-sori is reproduced from a photograph in 

 Fig. 213 (p. 526). 



A vertical section through a teleutospore-sorus is shown in 

 Fig. 216 (p. 537). Owing to the action of the fungus, the leaf above 

 an infected area undergoes hypertrophy so that it becomes depressed. 

 At the same time the teleutospore-sorus, which is usually developed 

 on the under side of the leaf, comes to bulge hemispherically down- 

 wards and thus gains an admirable shape for producing the maximum 

 number of teleutospores in a position for the successful discharge of 

 the basidiospores. 



The distance to which the basidiospores are shot was determined 

 in the following manner. A complete sorus of teleutospores was 

 removed by a section cut through it in the plane of the lower 



^ J. J. Taubenhaus, " A contribution to our knowledge of the morphology 

 and life history of Pxiccinia Malvacearum Mont.," Phytopathology, vol. i, 1911, 

 pp. 55-62. 



^ W. Robinson, " On some relations between Puccinia Malvacearum Mont, and 

 the tissues of its host plant [Althaea rosea),'' Mem. and Proc. of the Manchester Lit. 

 and Phil. Soc, vol. 57, 1912-1913, pp. 1-24. 



