12 Reproductive Organs. 



The germinal 4:ube or promvceliuni (by a j^rocess of ab.striction) proceeds 

 directlv to the formation of reproductive bodies, which diSer in no essential 

 particular from the Conidia similarly produced in other groups, and Brefeld 

 has adopted that term. But De Bary uses the name sporidium as originally 

 proposed by Tulasne for the promycelial spore in the Rusts, and considering 

 that the term had already been used for the ascospore in the Ascomycetes, 

 and Saccardo had therefore altered it to sporidiola. it will avoid the unnecessary 

 multiplication of terms to retain the old name of Conidium (Plate I., q, s). 



The typical description of the mode of germination will therefore be that 

 the spore produces its short germinal tube or promycelium, which in turn 

 gives rise to conidia. and there may be secondary and tertiary conidia 

 produced, or even those which sprout in a yeast-like manner, and are therefore 

 called sprouting conidia. Although I have adopted here, for the sake of 

 simplicitv, the term conidium for the product of the promycelium, it is not 

 to be regarded as necessarily different from the similar body produced in 

 the Rusts, for which the name of Sporidiolum was chosen. 



Structure. 



The spores are colourless at first, and gradually assume a brown or black 

 colour, which is confined to the outer thick membrane or exospore, while (he 

 inner or endospore is thin and remains colourless. The exospore is not only 

 coloured and thickened, but its surface may be either smooth or roughened 

 in various ways. It may develop spines, warts, or net-like markings, but 

 sometimes the markings are so minute as to be simply granular. 



The spores are either free, as in Usfilago, or united into spore-masses, as in 

 Sorosporium. This formation of spore -clusters is brought about by the 

 sporogenous hyphfe becoming densely interwoven, and when the spores are 

 subsequently formed they grow together, and so remain united in heaps. 

 If they are not thus hrmly united, the spores may occur in clusters, and yet 

 be easily separated, so that they belong to the free-spored forms. The division 

 to which they belong can only be definitely settlecl by tracing their develop- 

 ment and mode of formation, unless when they are permanently and not merely 

 temporarily united. It can readily be understood that there is no great 

 morphological difierence between the forms Math free and with united spores, 

 and even in the germination of the individual spores there is considerable 

 resemblance. But the distinction is well marked where the spores of a cluster 

 have a special envelope consisting of sterile cells, as in Urocystis. These 

 outer sterile cells not only protect the fertile inner cells, but probably serve 

 as floats to carry them to a suitable place for germination. The protection 

 to the spores has reached its highest development in Doassansia, where the 

 clusters of spores are enclosed in a highly speciahzed peridium, consisting 

 of densely packed sterile cells, reminding one of the protective cells in the 

 Gasteromycetes. and there known as a peridium. The spores thus protected 

 are able to remain under water for a considerable time, and they may germinate 

 either under water or on damp earth by the germinal tube bursting through 

 the envelope. 



Dispersion of Spores. 



As in the great majority of fungi, the wind is the most important agent 

 in distributing the spores. When the smut is produced in the ear or 

 inflorescence, as it generally is in grasses, it is in a favorable position for the 

 wind to play upon it, and the gentle swaying to and fro of the plants will 

 help to shake out the spores even in a still atmosphere. The spores thus 

 distributed may fall upon the ground, or be carried to healthy grains where 

 they attach themselves to the surface, as any small particles of dust might 



