i882.] Botany. 585 



the first appearance of the Hemileia is indicated by a slight trans- 

 parency or palish discoloration, easily noticed when the leaf is 

 held up to the light. These transparent spots indicate the points 

 where infection of the leaf has begun. As the spots becomes 

 larger and older, it assumes a faint yellow color ; ultimately on 

 the under side of the leaf, it becomes covered with a bright yel- 

 low dust, and this later on changes to a bright orange." 



Ward studied the development of the parasitic hyphae in these 

 spots, and found that after ramifying between the leaf-cells, from 

 which they ' 



§&-,^?<L 



stona(Fig. 1), they 

 develop in great num- 

 bers in the lacunae be- 

 \\J ^: !i \^) ■'YVX neath the stomata, 



JW\ through which they 



X7l- ° ,-^-Cj finally protrude. The 



l; ai \ apex of each hypha ex- 



11 which eventually ac- 

 trating lelf-cells° n ° f * hypha ^ haustoria pene - quiring a thickened, 

 roughened w a 1 1, be- 

 comes a spore (see Fig. 2), the uredospore, according to Ward. 

 Later the same mycelium gives rise in a very similar way to 

 smooth napiform bodies — the teleutospores (Fig. 3). 



a^ , m 



DC 



The germination of the uredospore (Fig. 4 a ) agrees with that 

 ?f the uredospore of ordinary Uredineee, one or more hyphse be- 

 ln g sent out from it, which eventually penetrate the leaf. This 

 was repeatedly seen in the many excellent cultures made by Mr. 

 Ward. The teleutospore germinates very readily, it being the 

 rule for it to do so while yet attached to its hypha.. A tube (the 



