150 THE AMERICAN MONTHLY [May 



ilicis and Trochila lauro-cerasi, are to be found on almost 

 every dead holly or laurel leaf. 



In the Sphaeriacei the conceptacles may be quite naked, 

 as in many species of Sphaeria, or more or less immersed 

 in a stroma or bed, which may be incrusting the branch 

 as in Diatrype ; formed into masses of various shapes as 

 in Xylaria (the candle-snuff fungus), Hypoxylon, and 

 other genera. In Nectria, one species of which is ex- 

 ceedingly common on dead stems of currant, etc., the 

 perithecia are usually clustered together and of a rich 

 red color, resembling, under a low power, a basket of 

 strawberries. The spores, too, are very various : some 

 are simple, hyaline, and shortly ovate or rounded, others 

 of various degrees of length, and one- or many-septate, 

 and colored ; some drawn out into veritable needles. 



Some of the Hyphomycetes, as already mentioned, are 

 known to be conidial fruit of certain ascigerous fungi ; a 

 third form of fructification is met with in the form of 

 minute perithecia containing naked spores, formerly 

 grouped under Sphaeropsidei ; in a fourth, long, glutin- 

 ous tendrils, consisting of myriads of simple spores are 

 met with, while in some cases — Sphaeria herbarum, for 

 instance — no fewer than five forms, once considered dis- 

 tinct genera and species, are now united as different 

 stages in its cycle of existence. 



Thus it will be seen that there is a great field open to 

 the investigator in working out the life history of these 

 organisms, which, though lowly and seemingly insignifi- 

 cant, are in many instances of great economic importance 

 from the injuries they cause to valuable crops and trees. 

 Such are the potato-blight, wheat-rust, vine-mildew and 

 many more. As to reference books, Dr. Cooke's "Micro- 

 scopic Fungi'' (Rust, Smut, Mildew and Mould) is of great 

 assistance to the beginner. The earlier editions fo it 

 were written when the relations between Puccinia and 

 iEcidium, Peronospora and Cystopus, etc., were scarcely 



