252 DIVISION II. — COURSE OF DEVELOPMENT OF FUNGI. 



exhibiting the same comparatively minute specific distinctions, but in which the 

 formation of an ascocarp such as belongs to the particular development 

 has never been observed, while at the same time there is no reason for considering 

 that they belong to any group outside the Ascomycetes. We are compelled by this 

 condition of our knowledge to regard these isolated forms as homologous with those 

 which are like them and the position of which is known in the course of development 

 of other species, and to call them accordingly spermogonia, gonidiophores, pyenidia, 

 or the like ; it is true that this practice is founded only on probabilities, but it has 

 already found its justification in many cases in the strict proofs which have been 

 subsequently obtained. Most of the Haplomycetes, Gymnomycetes, Sphaeropsideae, 

 &c. of the old systems, one might indeed say all of them that do not belong to the 

 groups described in the previous sections, fall in this way and in accordance with the 

 present state of our knowledge into the class of Ascomycetes, some connecting 

 immediately with well-known ascomycetous species, others through the forms first 

 mentioned ; the grouping of the very large number of species and particular 

 forms is necessarily attended with practical difficulties of a different kind from those 

 which are met with in dealing with the few dozen Mucorini or Peronosporeae. 



While referring the reader to the descriptive literature of this subject, it may be 

 well to mention a few names in illustration of the above remarks ; most species for 

 instance of the old form-genera Naemaspora, Cytispora, Libertella, Septoria, Lepto- 

 thyrium, Phyllosticta, Cheilaria, Gloeosporium, Spilosphaeria, Ascochyta, Phoma, 

 Diplodia, Myxocyclus, Hendersonia, Sporocadus, Sphaeropsis, Cicinnobolus, Ehr. and 

 some others must be classed with the pyenidia and partly also with the spermogonia ; 

 species of the form-genera Cylindrosporium, Oidium, Dematium, Conoplea, Periconia, 

 Cladosporium, Helminthosporium, Macrosporium, Dendryphium, Mystrosporium, 

 Brachycladium, Sepedonium, Mycogone, Aspergillus, Verticillium, Polyactis, Botrytis, 

 Fusisporium, Alternaria, Torula, Isaria, Stilbum, Atractium, Graphium, Melanconium, 

 Stilbospora, Steganosporium, Coryneum, Exosporium, Vennicularia, Tubercularia, 

 Sphacelia, and many others, whose affinity to undoubtedly typical Ascomycetes is either 

 certain or very probable, go with the filamentous gonidiophores and open gonidia- 

 bearing hymenia. To these may be united with the needful reservation a large number of 

 forms, in which the mycelium and the formation of spores, which must be considered 

 homologous with the gonidia, are all that is at present known. Some of these forms do 

 actually belong to the above form-genera, for the determination of these genera was made 

 to rest on certain particulars of conformation which in some cases appear to our present 

 knowledge to have been very superficially examined, and which, as we have since 

 learnt, may occur in very various genetic connections. For instance Oidium lcuco- 

 conium, Desm. and O. erysyphoides, Fr. are names for the gonidiophores of Erysiphcac. 

 Oidium fructigenum, Kzc. and O. lactis, Fres. are somewhat similar forms which do 

 not belong to the Erysiphcac and whose genetic affinities are quite unknown ; Botrytis 

 cinerea is the name of Sclerotinia Fuckeliana when it produces gonidia ; B. Bassii 

 denotes an isolated gonidial form by no means closely related to the last-named 

 Botrytis. Other forms of this series are so widely different from those named above 

 that the old describers gave them distinct generic names ; thus they called their 

 Hyphomycetous forms Arthrobotrys, Gonatohotrys, Haplotrichum, Cephalothecium, 

 Stysanus, &c. &c. 



These forms are for the present arranged with the Ascomycetes, because from 

 what we know of them they appear to have more connection with that division 

 than with other Fungi ; but they are only known to us under one form, which may be 

 considered to be that in which they produce gonidia. 



