142 
5. The chlamvdospores of Tulletia Tritict under the demonstra- 
tion microscope. Note the reticulated surface of the spores, the globose 
shape and smaller size. DRAW. 
Make a mount containing chlamydospores of both Ustilago Tritict 
and Tilletia foetens. Compare as to size, shape, color arid markings. 
DRAW to show the contrast. 
When the inoculated grains are planted, the spores of the pathogene 
are planted with them. The conditions which favor seed-germination 
also favor spore-germination. A promycelium is formed bearing sporidia 
which in turn produce germtubes capable of penetrating the seedling, 
but only at some point below the first node or tillering-point. Study the 
germinated spores provided, or figures in Washington Bul. 126:7, and 
OBSERVE :-— 
6. The germtube arising from the chlamydospores,—the promy- 
celium. From which side of the spore does it arise? 
7. The cluster of sickle-shaped sporidia at the end of the promy- 
celium. 
8. That frequently two of the sporidia have joined by a short 
tube forming an H-like figure. This is very common and was once sup- 
posed to be a sexual process but it is not now so considered. 
9. Some of the sporidia germinated, forming secondary sporidia. 
Make pRawincs to show chlamydospore-germination and formation 
of secondary sporidia, or copy from Minnesota Bul. 133, pl. XXIV and 
XXV. 
The germtubes from sporidia or secondary sporidia penetrate the seed- 
ling as it emerges from the grain and, branching, forms amycelium, This 
mycelium quickly reaches the growing-point and grows upward with the 
culm causing no apparent injury to the host. At the time of flower-forma- 
tion, however, the hyphae develop rapidly and, growing into the ovary, 
destroy the contents and replace them with the black spore-mass. 
REPORT 
1. A farmer who knows how to control stinking smut desires 
to understand the cause of the disease and just how it differs in this respect 
from the loose smut of wheat. Write him a letter giving this information 
in a form which he will understand. 
