20 



the ^^phmropsidei and Melanconiacem. Later, when ascigerous fungi 

 were separated from stylosporous fungi, this group was revised, the as- 

 cigerous species only being retained. As at present limited, the Pyrenomy- 

 cetes are " ascigerous fungi having the fructification enclosed within a 

 perithecium." 



They constitute a very large group, the described species, according to 

 Cooke's Census of Fangi, numberiog not less than 10,500, or at least 

 1,000 more than all the recorded species of Hymenomycetes. The plants 

 are microscopic in size, and grow upon vegetable or animal substances. 



HYPHOMYCETES. 



With regard to the Hyphomycetes, Cooke takes the ground that in their 

 internal relations to each other, and their external relations to the remain- 

 ing orders, the Hyphomycetes are undoubtedly a well-defined and natural 

 group, and should have place as such in a systematic work. It is a large 

 order, containing nearly 5,000 species, mostly parasitic on dead animals 

 and vegetable matter. The spores, termed conidia, are free, as in Hymen- 

 omycetes. The species are microscopic in size, and the hyphae are 

 strongly developed. They have no hymenium and no true basidia, and 

 are non-sexual in their reproduction. 



The four primary sections are the Mucedinese, or " white moulds ;" the 

 Dematiese, or "black moulds ;" the Stilbea, with the hyphae or thi'ead-like 

 filaments pallid or brown, and densely cohering, and the Tubercularieae, 

 with the hyphae densely compacted in wart-like pustules of somewhat 

 gelatinous consistency. 



The divisions called Melanconiese, Sphseropsideee, and Hyphomycetese 



are not recognized in the Brefield system of classification as distinct 



groups. Massee and Cooke, with other mycologists, take exception to 



this omission and its implication, in their discussion of the subject, 



giving consistent reasons for the retention of these groups in systematic 



works. 



PHYCOMYCETES OK PHYSOMYCETES. 



As originally defined by Berkeley', this group was composed chiefly of 

 the old typical Mucors and their allies, and was then termed Physomy- 

 cetes. In the newer system of classification its original definition has 

 been extended so as to include a number of groups somewhat dissimilar 

 in their habits and characteristics, but '' united under the conservating 

 bond of a dimorphic reproduction," and the name has been changed to 

 Phycomycetes. As at present recognized " the Phycomycetes are charac- 

 terized by a unicellular mycelium, often parasitic on j)lants or animals, 

 sometimes saprophytic, developed in the air or in water. Reproduction 

 sexual or asexual." As thus interpreted, Phycomycetes includes the 

 Mucoracei ; the Peronosporaceae, or " rotting moulds " ; the Cystopi, or 

 " white rusts " ; the Saprolegniaceae, or " fish moulds " ; the Entomo- 

 thoraceiB, or " insect moulds," together with a few minor groups of 

 doubtful natural affinity. 



