INTRODUCTION TO CBYPTOGAMIC BOTANY. 311 



though depending principally on colour, is so natural, that a 

 very slight practical knowledge is at once sufficient to detect 

 the species which belong to the section, without much chance 

 of error. The mycelium is seldom much developed, and the 

 fertile threads, which in some species are highly developed, 

 and generally very rigid, are in others reduced almost to no- 

 thing. In these cases the spores are larger, and the species 

 approach those of the next order. The spores differ very 

 greatly even in the same genus. In Helmintliosporium, for 

 instance, if genera are to be founded upon the spores alone, 

 there would be materials for several new names. In a few 

 cases they are simple and small, but in general they are highly 

 developed. In many species they are greatly elongated with 

 numerous septa, while in two or three they are curved into regu- 

 lar spirals. With a few exceptions they grow on exposed wood 

 or on dead vegetable subtances; and in one or two instances, as 

 in Sporoschisma, RelminthosporiuTn appears as a secondary 

 form of fruit. Gladosporium herbarum is perhaps the com- 

 monest of all Fungi, and is produced wherever dead vegetable 

 matter, not too highly saturated vdth water, is exposed to 

 climatic influences, and even animal structures are not safe 

 from its attacks ; other species occur in tropical countries. In 

 some cases, as in Gladotrichum, the fertile threads are very 

 highly developed, and the articulations of which they are com- 

 posed assume very curious forms, passing gradually into spores. 

 In Sforocyhe, as mAspergillus,ih& fertile cells are crowded Luto 

 globose heads, crowning the threads and supporting a Httle puff 

 of spores ; and in one of the species the sporophores are swollen, 

 and the spores which they sustain have a deciduous episporium. 

 Little is known of the species which affect other parts of the globe 

 than North America, Europe, and the Mediterranean coasts. 

 (Edemiiom and Macrosporium occur in New Zealand, and I 

 have a curious new genus from the Deccan (Fig. 71, b). The 

 mildew which attacks linen is often due to Gladosporium. 



4. Stilbacei, Berk 



Mycelium floccose or cellular ; stem or receptacle composed 

 of compacted threads or cells, the tips of which produce minute 

 diffluent spores. 



