INTRODUCTION TO CRYPTOGAMIC 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 

 aj^proach those of the next order. The spores differ very 

 greatly even in the same genus. In Hehninthospoi'ium, 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 Si^oTosckisma, Helminthosporium appears as a secondary 

 form of fruit. Gladosporium herbaruon is perhaps the com- 

 monest of all Fungi, and is produced wherever dead vegetable 

 matter, not too highly saturated with 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 CladotrichvAn, the fertile threads are very 

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

 posed assume very curious forms, jDassing gradually into spores. 

 In Sporocybe, as in A sper(jilhis, the fertile cells are crowded into 

 globose heads, ci'owning the threads and supporting a little puff 

 of sj^ores ; and in one of the species the sporojahores ai-e swollen, 

 and the spores which they sustain have a deciduous episporium. 

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

 than North America, Europe, and the Mediterranean coasts. 

 (Edemium and Macrosporium occur in New Zealand, and I 

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

 mildew which attacks linen is often due to Cladosporiurri. 



4. Stilbacei, Bevl^:. 



Mycelium floccose or cellular ; stem or receptacle composed 

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

 diffluent spores. 



