232 PRACTICAL BOTANY 



2. The masses of dark brown teleutospores or winter 

 spores, which are produced by this mycelium, each spore being 

 borne on a thin pedicel: each consists of two cells, with thick 

 walls, differentiated into two layers, the exospore and the 

 endospore. In the protoplasmic contents of each cell is a 

 clear spherical body, which may be the nucleus, but this is not 

 certain. 



III. If pieces of a Grass plant bearing teleutospores be kept 

 in a moist atmosphere (on wet blotting-paper, under a bell 

 glass) in the spring-time, a fine, white, semi-transparent growth 

 will be produced from the teleutospores: this is the promy- 

 ceiium. Remove some of these germinated teleutospores 

 carefully with a needle, and mount in water : if this be done 

 without injuring the promycelium, it will be seen under a high 

 power that one or both of the cells of the teleutospore have put 

 out a germinal tube (the promycelium) by rupture of the 

 exospore, and protrusion of the endospore : this promycelium 

 divides into four or five cells, each of which (excepting the basal 

 one) produces a conical process (the sterigma) : the end of each 

 of the sterigmata swells into a small irregularly roundish body 

 (the sporidium), which ultimately becomes detached. 



B. sEcidium Stage. 



IV. Note in early summer on the leaves of Herberts irregular 

 bright yellow or red blotches, the tissues of the leaf appearing 

 swollen at those spots, and projecting convexly on the lower 

 surface, while the upper surface of the blotch is usually concave: 

 on the lower surface numerous irregularly distributed yellow 

 cups (secidium cups) may be seen projecting slightly beyond 

 the surface, while on the upper surface also projecting organs 

 of smaller size, and irregular distribution (spermogonia) may be 

 seen. 4 



V. Cut transverse sections of a diseased leaf, so as to pass 

 through one of these blotches : mount some in glycerine, others 

 in chlor-zinc-iodine, and examine under a low power: observe 



i. That in the thinner normal part of the section, between the 

 upper and lower epidermal layers there is a mesophyll consist- 



