GOLDEN OR SPRING ' RUST 735 



glass slide and examine with a high power ; draw the basidia and basidio- 

 spores. 



Ex. 303. — Examine barberry bushes in May and June for ascidia of Puccinia 

 graminis. If found, make drawings of the parts as seen with a pocket lens. 



Cut transverse sections through the leaf so as to pass through one or more 

 secidia. Mount in water and observe with a high power the structure of 

 the single layer of cells forming the cup, the rows and shapes of the 

 spores. 



Ex. 304. — Shake out some of the spores from a fresh secidium into a dish of 

 water on a glass slide and place the latter on wet blotting-paper under a 

 bell-jar. Examine every twelve hours for germinated spores ; draw the 

 latter. 



Ex. 305. — In section from Ex. 303, note the presence of spermogonia on 

 the upper side of the leaf. Examine with a J or J inch objective and draw 

 the various parts seen. 



Ex. 306. — Where barberry bushes are uncommon or non-existent the secidia 

 of other species of the Uredineae should be utilised for a study of the structure 

 of this' stage in their life-history. 



They should be looked for in spring and early summer on species of 

 buttercup {Ranunculus), moschatel i^Adoxa moschatellina), species of dock 

 (Kuniex), wild violets, coltsfoot {Tussilago Farfara), and stinging nettle 

 ( Urtica dioica). 



8. Other species of Puccinia which, attack cereals. — In 

 addition to summer 'rust' or black 'rust' {^Puccinia graminis 

 Pers.), the following distinct species of 'rust '-fungi are met with 

 upon cereals. 



.{a) Golden or Spring 'Rust' (Puccinia glumarum Schm.) — 

 This species in the uredo-stage forms small cadmium-yellow sori 

 which are situated on elongated pale yellow patches upon the 

 leaves of the infected cereals. It is often alarmingly conspicuous 

 in spring, and in certain cases is liable to attack the glumes and 

 injure the grain later in the season. Most commonly, however, 

 it does little damage to the crop, and disappears without forming 

 many teleutospores. 



The uredospores are roundish and possess eight or ten germ- 

 pores which are difficult to observe except when the spores' 

 germinate. 



