8 



formal production in basidia are the same ; the difference consists only in the number of spores. 

 Therefore the Hemibasidia of the Ustilagineae have already the characteristic form of the basidia 

 but as yet no definite number of spores. The growth from the first stages up to the complete 

 basidium occurs first in the actual Basidiomycetes. The Ustilagineae are accordingly Hemibasid- 

 iomycetes. They pass over naturally in their types, once with divided hemibasidia, again with 

 undivided ones, in one direction to the Protobasidiomycetes, in the other to the Autoba- 

 sidiomycetes 1 . 



In the formal sphere of the Ustilagineae with Protohemibasidia, there is the interesting 

 addition in the formation of Hemibasidia that there exist forms, such as those, for example, 

 in Ustilago longissima and also in Ustilago grandis", in which the Hemibasidium has not yet 

 become typical in its formation and in which the conidia always grow out again to irregular 

 Hemibasidia. In Ustilago bromivora 3 , the hemibasidia have become typical, but the conidia 

 still grow out to hemibasidia. Only in the later forms of the genus, Ustilago ; for instance, Ust. 

 carbo, Ust. maydis, Ust. sorghi (cruenta 4 ), etc., the hemibasidium is limited in the germination 

 of smut spores to the single typical formation with conidia as subsidiary fruit forms, as in typical 

 basidiomycetes. In this limitation the gradtion is shown, through which a hemibasidium attains to 

 its highest formation. Compare the detailed illustrations in Part XII, where the new nomencla- 

 ture is based on a phylogenetic foundation. 



In the entire province of morphology, cases of natural relationship passing from the simple 

 to the more complex cannot be ascertained in as clear and convincing a way as they exist here in 

 the forms of hemibasidiomycetes and actual basidiomycetes. This elucidation of the peculiar 

 formation of the basidia has become one of the now immovable supports of the natural classi- 

 fication of fungi, as based on the comparative morphological foundation in the last VI Parts of 

 this work and completed therein. 



This is the unexpected outcome of the germination of smut spores in nutrient solu- 

 tions from the phylogenetic side, in the consideration of the natural classification of the fungi. 

 It leads to the natural valuation of the basidium and through this alone to an understanding of 

 how the course of morphological differentiation has taken place in the direction of the basidia. 



Besides this, however, these new facts have given new and important elucidations of the 

 saprophytic life of these fungi from another point of view. The theory previously held, accord- 



(1) We are here involuntarily reminded of TULASNE, who designated the fructiflcatiye germina- 

 tion in the Ustilagineae and in the Uredineae jointly, on the ground of their formal correspondence, as 

 germination in promycelia and sporidia. TULASNE had observed germination of these spores only in 

 water where no differentiation at all is shown in the promycelia of the Ustilagineae and the Uredineae. 

 The characteristic formal variation existing between these, however, can be determined only by culture of 

 of the spores of the Ustilagineae in saprophytic nutrient substrata instead of in water. Here TULASNE'S 

 promycelia in the Ustilagineae were first proven to be Hemibasidia in contrast to those of the Uredineae, 

 whose promycelia are shown by comparison to be typical basidia, Protobasidia.. As has already been 

 said, TULASNE suspected the natural relationship of both sets of forms, but a determination of the 

 characteristic differences existing between the two types was not granted him. This was first made 

 possible by the improved methods in the culture and investigation of fungi which I introduced and 

 chiefly by the fact that I broke through the conception held until then, according to which the parasitic 

 fungi, and here especially smut fungi, are dependent for development only on their host plants. 



(2) Compare plates VIII and IX in Part V. 



(3) Compare plate X in Part V. 



(4) Compare plates II, III, IV and VII. 



