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Pomona College Journal of Economic Botany 



of both species arc dark, heavy, and thick-walled, but differ greatly in size and 

 position. Those of Scleroplea aurantiorum (Figure 45B) are almost entirely 

 below the surface level of the leaf, while those of the Mycosphaerella (Figure 45A) 

 are merely beneath the epidermis, rupturing the latter as they grow. The peri- 

 thecia, asci, and spores of Scleroplea aurantiorum are quite uniform in size and 



Figure 45. Details of Scleroplea aurantiorum and Mycosphaerella lageniformis. 

 A, a, a, a, M. lageniformis; B, b, S. aurantiorum. 



form, as shown in the figures (B and b). The black perithecia, together with the 

 yellowish, opaque spores in the transparent asci, are very striking in appearance. 

 The asci and spores of Mycosphaerella lageniformis * however, are neither con- 

 spicuous, nor uniform, although the perithecia do not seem to vary much. The asci 

 may be of almost any shape from the typical flask-shape described by Mr. Rehm, 

 to long, cylindrical. The spores, like the asci, are hyaline and not uniform in size, 

 although they are easily distinguished by their shape and two-celled structure. 

 Something of the variation found is shown by the figures of the six asci given, 

 (Figure 45, a a a). 



*A Mycosphaerella with similarly lageniform and very variable asci has 

 recently been described by Shirai and Hara under the name of M. macleyae from 

 Macleya cordata in Japan (The Botan. Magaz. XXV, March, 1911). 



