132 DIVISION II. COURSE OF DEVELOPMENT OF FUNGI. 



the fact that the two forms were most certainly homologous. This was the case in 

 the Mucorini ; see Brefeld, Schimmelpilze, IV. 141, and sections XLI-XLIV below. 



It is then quite clear that only the homology and not the mode of origin determines 

 the nature of the structure in this case, and that conidia may be formed endogenously 

 and even in an ascus, as well as acrogenously. On these grounds Fries' venture in 

 terminology is not a happy one, and it would be desirable to discard the word 

 conidium and employ gonidium in its stead. The confusion pointed out above would 

 thus be avoided, and homologous structures would be named alike with one generally 

 applicable name in Fungi and in all other plants. We need not at the present day 

 trouble about the special terminology of the Lichens, in which the word gonidium has 

 hitherto had a special meaning, because as there used it is not only superfluous but 

 objectionable, as will be shown in Division III. Moreover its application in the sense 

 explained above is only a restoration of the meaning which its author Wallroth 

 intended to give it, though under a misunderstanding of the facts. 



For further details on this subject the reader is referred to Tulasne's Carpologie, I. 

 chapter VI. 



SECTION XXXVI. According to the leading points of view here indicated and 

 the present state of our knowledge a review of the course of development of the 

 several groups of the Fungi arranges them in the following manner : 



I. SERIES OF THE ASCOMYCETES. 



1. Peronosporeae (with Ancylisteae and Monoblepharis). 



2. Saprolegnieae. 



3. Mucorini or Zygomycetes. 



4. Entomophthoreae. 



5. Ascomycetes. 



6. Uredineae. 



II. GROUPS WHICH DIVERGE FROM THE SERIES OF THE 

 ASCOMYCETES OR ARE OF DOUBTFUL POSITION. 



7. Chytridieae. " 



8. Protomyces and Ustilagineae. 



9. Doubtful Ascomycetes (Saccharomyces, &c.). 

 10. Basidiomycetes. 



Groups 1-4 have been brought together under the name of Phycomycetes 

 on account of their close approximation to the Algae. 



Groups 7 and 8 in the second category will be considered in connection with 

 the Phycomycetes; group 9 naturally in connection with 5, and 10 with 6. 



CHAPTER V. COMPARATIVE REVIEW OF THE SEPARATE GROUPS. 



PERONOSPOREAE. 



SECTION XXXVII. Of the Peronosporeae some species of Pythium live in 

 the bodies of dead animals and plants, the greater number as parasites in the tissues 

 of Phanerogams, and chiefly in the intercellular spaces of the host, though there 

 are species which, like Phytophthora omnivora, also spread through the cells. The 

 vegetable thallus consists of copiously and regularly branching tubes, which are 

 at first non-septate, but are divided into chambers at a later time when sexual organs 



