CARPOSPORE.E. 



331 



spring and form promycelia, from the sporidia of which the myceHa which bear the 

 secidium-fruits are developed. 



On comparing this second case with the first it becomes evident that here 

 several generations of mycelia are intercalated between the formation of the secidio- 

 spores and the formation of the promycelium. These generations give rise to 

 peculiar reproductive cells, the uredospores and the teleutospores. 



A sexual act has not as yet been observed even in these well-known forms of 

 jEcidiomycetes. If, however, we adhere to the rule that in the Thallophytes, as in 

 Cryptogams generally, the most complex form of development is the result of a 

 sexual act, and if we assume that an act of this kind does actually take place in this 

 case, we cannot but regard the aecidium-fruit as the sexually-produced generation ^ 

 The secidiiim-fruit will then correspond to the fructification of the Ascomycetes, the 

 [ecidiospores to the ascospores, and the uredospores, teleutospores, and sporidia to 

 various forms of conidia. Should these probable assumptions be substantiated by 

 future discoveries, it becomes at once evident that the nomenclature of the genera 

 must be based not upon the forms bearing teleutospores, but upon those bearing 

 aecidia, for instance the genus now known as Puccinia will have to be reconstituted 

 under the name oi JScidium^ the genus Gymnosporangium under that oi Roestelia, &c., 

 just as among the Ascomycetes not the conidia but the sporocarps aff'ord the basis 

 for their systematic arrangement. 



That the uredospores and teleutospores are merely forms of conidia is demon- 

 strated by the fact that they are present in some genera and species and absent in 

 others, resembling in this respect the conidia of the Ascomycetes. They are both 

 absent in E?tdophyllum, the uredospores are absent in Roestelia^ and both are present 

 in JEcidium Berber idis and in JEcidium Leguminosarum. 



The view which is here maintained is exclusively founded upon the well-known 

 forms. There remains a much larger number of forms of which the life-history is 

 only imperfectly traced. In a series of forms, for instance, the aecidium-fruits only 

 are known {jEcidium elatinum, Pint, abietinum'^, &c.), and it is still uncertain whether 

 or not they reproduce themselves by the aecidiospores alone : in others only the 

 teleutospores are known {Chrysomyxa, Puccinia Dianihi, compactd) : in others again 

 only the uredospores {CcEoma pinitorquuni): uredospores and teleutospores, without 

 gecidium-fruits, are known in Melampsora and Coleosporium. The last-named cases 

 recall Penicillium and Eiiroiium in which, formerly, only the conidia were known 

 and not the true fructifications, but they differ from them in that they possess two 

 kinds of conidia. It appears that, like Penicilliimi and other Ascomycetes, certain 

 ^cidiomycetes can reproduce themselves for many generations solely by means of 

 their conidia (uredospores and teleutospores) without attaining the completion of 

 their development in the formation of a true fructification (aecidium). 



The formation of the fructification of the ^cidiomycetes, like that of many 

 Ascomycetes, is accompanied by the development of peculiar receptacles, the 



^ To this view I drew attenti»n in the first edition of this book (1868). Oersted, loc. cit., and 

 Brefeld also support it. [See also Stahl, Bot. Zeitg. 1874.] 



^ [The life-history of JEc. ahielinum has since been traced by De Bary (Bot. Zeitg. 1879)". The 

 mycelium bearing uredo- and teleutospores infests the leaves of Rhododendron ferrugineum and 

 hirsutuin.'] 



