DOTHIOKA. 24& 



Dothiora. 



The spherical apotheeia are embedded in the substratum, which 

 they rupture into lobes, while they themselves dehisce by 

 irregular fissures. The club-shaped asci contain eight colourless 

 or yellow, club-shaped or spindle-shaped, multicellular spores. 

 Paraphyses are never present. 



Dothiora sphaeroides (Pers.) is regarded by Eostrup as the 

 cause of a disease of the Lombardy poplar (Populus pyramidalis), 

 in which the branches, particularly those of the upper part 

 of the tree, die one after another till all are gone. The spores 

 are club-shaped and constricted at the middle ; each half is 

 divided by four or five cross-septa, and each cell so formed 

 is again subdivided by a longitudinal septum. 



Vuillemin ascribes the same disease to Didymosphaeria 

 populina Vuill. (see p. 218). 



According to Eehm, Bo. sphaeroides also occurs on Populus 

 tremula, and is distinguishable from Do. mutila (Ft.) on both 

 Populus italica and P. tremula. 



Heterosphaeria. 



The spherical apotheeia are at first embedded, but later emerge 

 through the covering layers and dehisce, their apices breaking 

 up into teeth-like lobes ; they are dark-brown or black in colour. 

 The asci are club-shaped and contain eight spores, which are 

 colourless, oblong or club-shaped, and consist of one, two, or 

 four cells. Iodine colours the pores of the asci blue. The 

 paraphyses are colourless and thread-like. 



Heterosphaeria Patella (Tode). (Britain and U.S. America.) 

 The asci contain eight bicellular spores. The paraphyses are 

 thread-like and septate, some being forked or branched ; they 

 bear scalpel-shaped conidia. 



The mature apotheeia are found chiefly on the stems of 

 various Urribelliferae, e.g. Daucus Carota, ATiethum graveolens, 

 Petroselinum sativum, Pastinaca, etc. A variety alpestris occurs 

 amongst the mountains on Heracleum Sphondylium, also on 

 Gentiana lutea, Veratrum viride, etc. Eehm and others believe 

 that the fungus attacks living green parts of plants, and reaches 

 maturity in the following year on the killed organs. 



