250 BOTANICAL GAZETTE , [october 



Pycnidial stage of Meliola(?) camelliae (Catt.) Sacc. 



This pycnidium was studied from herbarium material collected ^ 

 by Dr. F. L. Stevens in Porto Rico. The fimgus, which usually 

 is reported as M. camelliae and is perhaps better known as "sooty 

 mold" (48), is plainly not a true Meliola, as the genus is limited by 

 recent writers (16, 40), and the position of its ascigerous stage has 

 not been definitely determined. 



A small pycnidium arises from a single cell of the main hypha 

 or a single cell of a h3^hal branch. The initial cell is usually an 

 intermediate cell, but it may be a terminal one. In either case it 

 divides by transverse and diagonal walls into 2, then 4 cells 

 (fig. 133), and by swelling and dividing becomes an elliptical, 

 finely reticulated, dark brown body (figs. 134-137). The mode is 

 simple meristogenous. 



These observations do not essentially disagree with the descrip- 

 tions as given by Zopf (53) and Tulasne (43), who studied early 

 stages of the development of the pycnidium of the sooty molds. 



Discussion 



Two main methods of origin and early development are found 

 in pycnidial formation, namely meristogenous and symphogenous. 

 The meristogenous method resolves itself into 2 modes, simple 

 (figs. I, 2, 4, 5) and compound (figs. 18, 22, 37). In the simple 

 mode the pycnidium develops from a single cell or a few adjacent 

 cells of a single hypha. In the compound mode adjacent cells 

 of 2 or more contiguous hyphae divide, swell, and sometimes 

 branch, all of these then anastomosing freely to form a pseudo- 

 parenchymatous mass. Variations of these 2 modes are found in 

 Macrophoma citrulli (figs. 39, 43, 47), Coniothyrium pyriana 

 (figs. 69-71), Septoria polygonorum (figs. 76, 77), Sphaeronaema 

 fimhriatum (figs. 5c»-52), a^nd Sphaeronaemellafragariae (figs. 82-85). 



The symphogenous method (figs. 48, 49, 54, 55) is less often 

 found in the species studied. In this method of development, 

 branching hyphae from main mycelial threads are directed toward 

 a common point, loop back, and interweave to form a loose network 

 which later becomes more close. The hyphae of this ball anasto- 

 mose into a pseudoparenchymatous mass from which the pycnidium 

 develops. 



