NAPICLADIUM. 517 



become coated with eonidia and assume a leaden grey colour, 

 so that in many cases only the points remain green. Finally 

 the attacked leaves die and dry up. 



4. Sect. Dictyosporae. 



1. Subsect. Micronemeae. 



The forms included under genera of this group (e.g. Sporo- 

 dcsmium and Coniothecium) have as yet been little investigated 

 in regard to their parasitic nature. 



2. Subsect. M^aeronemeae. 



Macrosporium. 



Conidia grey, murifomi, and lionie on the apex of simple or 

 branched cniii(lio})hores. 



Macrosporium sarcinaeforme Cav.^ Cavara describes a 

 browning and death of a whole field of red clover {Trifolium 

 pratense), and ascribes it to this fungus. Minute spots were 

 produced, at first light-coloured, then brown, finally coalescing 

 so as to cause drying-up of the whole leaf. The short thick 

 conidiophores were developed on the lower surface of the leaf, 

 and gave oft' pluricellular terminal conidia. 



M. solani Kll. et Mart. This is described- as occurring ahuig 

 with the " black-rot " of the tomato in the United States. It is 

 said to cause a rot in the fruit and a leaf-blight on l)oth tomato 

 and potato. Along with this species there also occur a Fumrium 

 (p. 520) and frequently a Clado.'iporium ; as yet the relationships 

 of the different forms, and the part they take in causing tlie 

 diseases ascribed to them, is but imperfectly investigated. 



Sorauer^ ascribes a disease on the potato in (Jermany to this 

 species or to an Alternaria {A. solani). He also believes that 

 it is the cause of the " early blight " of American potato crops, 

 but further investigation is still required. 



Many other species of Macrosporium have been described on 

 plants of economic importance, yet most of them occur only on 

 parts somewhat faded or languid, so that they cannot be regarded 



'Briosi and Cavara, Fumjhi jmrasil., v. 



-Report of the Sertion of Ver/etahle Patholo<jy for 18SS, U.S. Department of 

 Agriculture. 



^ Zeitichi-ift f. Pflanzenkrcuikheiti-n, 1896, p. 1. 



