xxv.] CORN MILDEW AND BARBERRY BLIGHT. 191 



and 8 1 in this work, but that Uromyces and even ^Ecidium 

 itself are both potentially capable of giving rise to precisely 

 the same growths. The pro -mycelium and pro -mycelium 

 spores of Uromyces are shown at B and C, and the same 

 growths belonging to the dScidium at F and G. The 

 phenomena are also exactly the same in regard to the 

 habit of pro-mycelium spores ; one belonging to Puccinia 

 graminis, Pers., as illustrated by Tulasne, is shown germi- 

 nating and producing a sporidiole (as Tulasne terms it) at 

 D, and a pro-mycelium spore of ^Ecidium is producing a 

 sporidiole of precisely the same class at H. 



It may be well here to glance at the development of the 

 teleutospores in Puccinia. We will take P. Rubigo-vera, 

 D.C., as an example. The teleutospores, which are preceded 

 by simple Uredo spores, first appear as short stalks capped 

 by a small cell, as at A, Fig. 89, enlarged 500 diameters. 

 At first the young teleutospore somewhat resembles a 

 Uredo spore as illustrated. Although this young teleuto- 

 spore looks like a Uredo spore in size and shape, it is in 

 reality quite different in nature. Botanists familiar with 

 these bodies can instantly recognise the two forms. Uredo 

 is probably a pupa state of Puccinia ; we do not say Puc- 

 cinia needs a pupa state, but that a state analogous to a 

 pupa stage often occurs, and is certainly present in both 

 the species of Puccinia which cause mildew of corn. In 

 an early stage of growth the young teleutospore has but 

 one cell- wall, and the material within is a watery fluid. 

 As growth progresses the spore is seen as at B, with a new 

 growth springing from the base within the original cell ; 

 this growth goes on till the spore resembles C ; the 

 internal mass has now formed another wall round itself 

 within the original wall, and in the course of a few days 

 the new inner cell will nearly occupy the whole of the 

 space within the first formed cell. At this time a third 

 growth appears at the base, as at D. This growth often 

 pushes the first inner cell aside, as shown, giving the one- 

 sided appearance often so common in Puccinia spores. 



