Vol. XIV, No. 9— Botanical Gazette -Sept., 1889. 



The Uredo-stage of Gymnosporanginm 



H. M. RICHARDS. 



(with PLATE XVII.) 



In the Botamsche Zeitung for June 22, 1888, there ap- 

 peared a paper by Kienitz-GerlofF entitled, " Die Gonidien 

 von Gymnosporangium clavarieeforme," in which he describes 

 the presence of two forms of spores in the gelatinous fruit mass 

 of that fungus. Although both are two-celled and of about 

 the same size, they may, he says, be easily distinguished. 

 Those found on the inside of the spore mass are symmetrical, 

 having thin hyaline walls and finely granular contents, while 

 on the other hand the spores more generally present on the 

 outside are not symmetrical, the upper cell being much 

 blunter than the lower one. Their walls are dark brown 

 and more than twice as thick as those of the first form, and 

 their contents are not granular. It is in their method of 

 germination, however, that he sees the most important dis- 

 tinction. The thick-walled spores always send out promy- 

 celia of the form which is characteristic of teleutospores. In 

 the thin-walled spores it is entirely different. In these he 

 observed two cases where the end of the spore grew out in a 

 tube, the contents of which did not divide up into cells and 

 bear sporidia, but remained unbroken, resembling in this the 

 method of germination characteristic of uredospores. He 

 also noticed a singular fact, that, instead of the endospore 

 penetrating the exospore as is usual, the whole end of the 

 spore grew out without rupturing the exospore. 



From their general dissimilarity in shape and structure, 

 and from their peculiar method of germination, he concludes 

 that these thin-walled spores represent the hitherto unknown 

 uredosporic form of G. clavariaiforme. Were their morpho- 

 logical characters and the method of germination constant, 

 it would be quite possible that the thin-walled spores might 

 represent what he claims. As the uredosporic form has not 

 before been recognized in any of the Gymnosporangia, it 

 seems highly desirable that the view advanced by Kiemtz- 

 Gerloff should be tested by an examination of American spec- 



