/,//(■ //isiofii's of \ arid IIS CJrass Smuts. 125 



In a iiutritve solution Brefeld found that the spore puts forth a germinal 

 tube, which is larger and more robust than that produced in water. It soon 

 divides into two cells, and this short promycelium produces couidia. These 

 conidia soon fall away, increase in size, and become uniseptate and behave 

 like the promycelium from which they sprung in producing secondary conidia, 

 hence Brefeld calls them bicellular sporophores. This formation of primary 

 promycelia from the spore and of secondary promycelia from the conidia 

 continues until the nutritive solution becomes exhausted. In more dilute 

 nutritive solutions the promycelium itself as well as the sporophores give off 

 mycelium-like tubes, and fuse in various ways. 



U . hromivora is thus characterized by its conidia growing into bicellular 

 sporophores, which sprout directly into new conidia. True sprouting conidia 

 do not occur. 



Infection. 



When seed is sown with adherent spores infection readily occurs, and in 

 a favorable season the smutted seed produced plants in which not a single 

 one escaped the disease. In this instance the seed was not artificially in- 

 fected, but just as it was received from the seedsman (Fig. 14), and it shows 

 how efficient this mode of infection must be in this particular species of 

 smut. 



Treatment. 



When the seed is treated with bluestone or formalin, as in the case of bunt, 

 the spores are destroyed and no infection occurs. 



3. Kangaroo Grass Smuts. 



(a) Cintractia exserta, McAlp.; 



{h) Sorosporium enter omor f hum, McAlp.; 



(c) Tolyposporiwm hursum (Berk.) McAlp. 



There are three smuts known on the Kangaroo grass in Australia belongmg 

 to the three genera of Cintractia, Sorosporium, and Tolyposporium respec- 

 tively. They are not as yet known to do much damage, except in certain 

 districts, but that may be simply owing to the fact that they have hitherto 

 escaped notice. They are all confined to the spikelets, distorting and de- 

 stroying them. 



(a) The Cintractia smut is very characteristic, since it stands out from the 

 glumes as an elongated greyish membrane enveloping the spores and the long 

 rigid awn of the healthy plant has generally disappeared (Plate X\T., B. ('.). 

 Wlien a cross-section is made towards the base of a diseased spikelet the 

 formation of the spores is clearly seen. There is a central core of plant tissue, 

 and surrounding this is a colourless mass of fungus filaments, from which the 

 spore-forming hyphae proceed. As the spores are formed inside, from the 

 centre outwards, the walls of the hyphae deliquesce and become gelatinous, 

 and the final result is that a dense mass of spores is formed inside the envelop- 

 ing membrane. This membrane gradually decays and the mature spores are 

 exposed. 



The germination of the spores has not been observed. 



{h) The Sorosporium snmt has received its specific name from the ehmgated 

 and puckered membrane which encloses the spores, being often twisted uj)on 

 itself, and resembling the intestine (Plate XVI.. A.). The spore-balls arc 

 composed of spores which hang loosely together, and they ultimately escape 

 by the decay of the membrane. 



Their germination is not known. 



