1 6 British Ui'cdinccB and UstilaginecE. 



wort in a Pasteur's flask, with Uredine yeast-spores, were 

 with me unsuccessful. The spermatia do not germinate in 

 pure water, but only in the presence of sugar. There is, 

 however, often enough saccharine matter in the investing 

 jelly of the exuded globule for a few of them to bud, 

 as Mr. Lister's figure shows, and as I have several times 

 observed. 



Rebentisch * noticed the small black points which the 

 spermogonia present in the spots upon pear leaves, on 

 which Rcestelia cancellata are produced. Ungerf figures 

 these structures, and describes them as a distinct species 

 under the name ^a^/^/^/w exantJicmaticwn ; he regarded 

 them as a peculiar exanthem of the affected plant. Meyen J 

 thought they played the part of the male element in the 

 reproduction of the Uredineae, with which they were asso- 

 ciated. Tulasne § considered they were spore-forms 

 developed from the same mycelium as their accompanying 

 spore-forms, but, like De Bary, was unable to observe their 

 germination. 



The spermatia of the Uredinese occur with all the 

 spore-forms. They almost invariably precede and accom- 

 pany the secidiospores, being produced from the same 

 mycelium, but generally occupying the upper surface 

 of the leaf, while the aecidial cups occur on the lower. 

 The first formed spermogonia are produced in the centre 

 of a spot ; the next more externally, and so on centri- 

 fugally. In many cases, however, they occur on the same 

 surface and between the secidia. When the secidiospores 

 are cauline, the accompanying spermogonia are often 



* Rebentisch, " Prodrom. florae Neomarch," 



t Unger, "Die Exantheme der Pflanzen," t. iii. figs. i8, 19. Wien : 

 1836. 



X Meyen, " Pflanzenpathologie " (1841), pp. 143-147. 



§ Tulasne, Comptes lendus, tome xxxii. p. 472 ; and tome xxxvi. p. 1093. 



