IMPERFECT CAPSULAR FUNGI— SPHAEROPSIDEAE 273 



has to contend, or, at the least, the most insidious, and least 

 subject to control. They do not spread over such tracts as the 

 potato disease and the hop mildew, but the infected plants upon 

 which they appear are doomed, and these often the rarest 

 and most valuable. The first external indication is usually in 

 the form of small elevations of the cuticle, or little warts, 

 which cover the concealed pustules ; for a long time these re- 

 main unbroken, but when the sporules are mature the cuticle 

 is ruptured, and a globule, or tendril, of agglutinated sporules 

 emerge through the orifice. These sporules are either elliptical 

 or elongated, usually much longer than broad, and often of 

 considerable size, but without septum or colour. Including 

 the two supposed genera, not less than some 230 species are 

 known, to say nothing of Marsonia, which is a corresponding 

 genus with uniseptate sporules, and similar habit and propen- 

 sities. The two corticolous genera Myxos2Jorium and Melano- 

 stroma are not clearly distinct from each other. The habit 

 is similar to Gloeos]Jormm, but the species are found chiefly on 

 dead bark, and therefore not parasitic, or destructive. Many 

 of the species are credited with being stylosporous conditions 

 of various ascigerous Fungi. The sporules resemble those of 

 Gloeosporium. The series of genera in which the sporules are 

 produced in chains is represented by only a few species. 

 Hypodermium has black pustules, which, being elongated, re- 

 semble the perithecia in Hypoderma, a genus of the Hysteri- 

 aceae. Myxosporella is simply Myxosporium with the sporules 

 catenulate. Blennoria has discoid pustules, which bear a re- 

 semblance to Puccinia, to which Agyriella is closely allied ; but 

 the pustules are at first gelatinous, becoming hard and shining. 

 In Trulhda the pustules are compact and erumpent, often 

 having the appearance of perithecia ; the sporules are sometimes 

 coloured. In the two genera Myxormia and Bloxamia the 

 pustules are apparently pezizoid ; that is to say, the form re- 

 sembles a shallow cup, or concave disc, without a receptacle. 

 In Myxormia the sporules are joined in a chain, by a narrow 

 isthmus ; and in Bloxamia they are truncate, and closely applied 

 to each other. There are two other genera, Colletotrichum, 

 which is simply a Gloeosporium, with the margin of the 

 pustules hairy ; and Pestalozziella, in which the sporules are 

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