ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 877 



constantly present in the nearly related genus Cop-inus. It con- 

 stitutes an addition to Koumeguere's list of bymenomycetous fungi 

 which produce " ozonium." 



Brefeld's Ustilagineae.* — The 5th part of Brefeld's ' Botanische 

 Untersuchungen iiber Hefepilze ' is occupied with the Ustilagineae. 

 In 23 species — including nearly all that are parasitic on our corn-crops 

 — he describes the mode of germination of the spores in specially 

 prepared nutrient fluids ; and this is followed by a discussion of the 

 morphology and systematic position of the family. 



The spores of many Ustilagineae require for their germination a 

 substratum rich in nutrient substances ; in pure water they either do 

 not germinate at all, or the weakly germ-plants soon perish. In 

 many species the second form of fructification, the conidia, appears 

 with the germination. They are either formed on a small carpo- 

 phore, the promycelium and sporidia of authors, ' or arise directly 

 from the spores. But in some forms the conidial fructification is 

 entirely suppressed. The conidia have the power of reproduction in 

 endless generations, either by means of carpophores with or without 

 mycelium, or by direct budding; in the latter case they appear in the 

 form of colonies of buds with independent power of growth, and 

 altogether correspond to the structures hitherto known as " torula " 

 or " yeast," and described as independent forms of fungi. In many 

 Ustilagineae the development of the two forms of fructification is 

 dependent on the conditions of life. When they are parasites, spores 

 only are formed on the mycelium ; but, on the other hand, when 

 living outside the host as saprophytes, conidia only are formed in an 

 endless series of generations, if there is no deficiency of nutrient 

 material. 



It is extremely probable that the conidial fructification in the 

 form of torula-like buds occurs also in nature in many species be- 

 longing to the Ustilaginea3 ; that they have therefore the power of 

 propagating outside the host as torulee, and develope their typical 

 spore-fructification only when they penetrate the tissues of the host 

 by means of germinating filaments, which takes place when the supply 

 of nutriment decreases. 



It is not, however, the Ustilagineae only that are distinguished 

 by the power of forming torula-like conidia. In a great variety of 

 classes of fungi forms occur the conidia of which can propagate as 

 torulge without carpophores by direct budding. 



These observations are obviously of the greatest importance, both 

 as regards the systematic position and morphological value of the 

 organisms hitherto known as torulsB, and with reference to the 

 diseases to which corn-crops are subject. It still requires to be 

 ascertained whether the saprophyte which has proj)agated itself for 

 generations in the form of torula can return to a parasitical condition, 

 and to the formation of spore-fructification connected with this condi- 

 tion ; and especially whether this is the case with the yeast-fungi. 



* Brefeld, O., ' Botan. Unters. iiber Hefepilze.' Heft v., 202 pp. (13 pis.). 

 4to, Leipzig, 1883. See Oesterr. Bot. ZeitscLr., xxxiii. (1883) p. 267. 



