ATyccliitiu of the Urcdiiieo'. '/ 



similar circumscribed dead area surrounds those sori of 

 P. annularis which are formed late in the year, and that 

 it is by means of teleutospores contained in these sori that 

 the fungus is reproduced in the following spring. 



The localized mycelium of the aecidiospores especially, 

 has a powerful influence upon the chlorophyll, causing it 

 to lose its green colour, and, as De Bary * has pointed out 

 with R. cancellata, making it disappear entirely. The 

 affected tissue is found to contain an immense number of 

 minute starch granules. To such an extent does the 

 development of starch take place, that in the Himalayas 

 the natives eat the hypertrophied stems of Urtica parvi- 

 folia, which are affected with Aic. nrticcs, on account of 

 the abundant nutritive starchy material they contain. 

 The hypertrophies are eaten just before the aecidia open, 

 and are said to resemble cucumber in flavour.f The 

 affected places generally assume some tint of yellow or 

 reddish yellow, more or less bright. In the Polygoneae the 

 spots are bright red or purplish {Aic. runiicis,Uredo bifrons). 

 In other cases they are yellow, surrounded by a purplish 

 or reddish border (^r. zonalc, behenis). In a few instances 

 all colour is more or less discharged, and the spots appear 

 whitish {/Ec. albescetis, leiicospei'Diunt). 



The mycelium of all species is by no means thus 

 localized. With some Uredines, on the contrary, it per- 

 vades the whole plant with the exception of its roots — 

 stem, leaves, petioles, peduncles, and the upper part of 

 the root-stock. De Bary % has shown that when the 

 mycelium of a Uredine can be traced into the perennial 

 parts of the host-plant, it is itself perennial ; thus with 



* De Bary, " Brandpilze," p. 73. 



t Surgeon-Major A. Barclaj-, " On ilicidium Urtic?e," "Scientific Memoirs 

 by Medical Officers of the Indian Army" (1887), p. 2. 



X De Bary, " Neue Untersuchungen iiber Uredineen '" (1S65), pp. 20, 21. 



