MiCROSPHAERA 151 



On the whole, the present plant appears clearly marked off 

 from typical M, aim by the long flaccid appendages, and their 

 usually more irregularly branched apex. It is more difficult to 

 separate it from M. alni var. cxtcnsa, I do not think it advisable 

 at present, however, to unite these two forms. In the var. vac- 

 cinii the apex of the appendages is almost constantly more irregu- 

 larly and widely branched than that of the var. cxtcnsa, indeed the 

 primary branches are sometimes long, div^ergent, and slightly re- 

 flexed as in the var. divaricata. In the var. cxtcnsa the apex is 

 usually as ornate and as closely branched as in certain forms of 

 typical M. alni. It must, however, be mentioned that cases have 

 occurred, although very rarely, where the apical branching of the 

 var. vaccina has been quite similar to that of the var. cxtcnsa^ and 

 it is certainly possible that these two varieties will eventually have 

 to be united. 



I feel no hesitation in considering-^ clcvata Burrill, on Catalpa^ 



as a form of the present plant. 



At first sight this form, which occurs on Catalpa bignonioidcs 

 and C. speciosa appears to have these distinctive characters : 

 smaller perithecia with fewer appendages, and a smaller more 

 closely branched apex. The size the perithecium, however, is 

 certainly variable, not only in this form on Catalpa^ where it ranges 

 from 70-1 30 /i in diameter, but also in the plant on Vacciniiun and 

 Epigaea, In Cooke & Peck's type of M, vaccinii at Kew, the 

 perithecia, although varying between wide limits, average 115/^; 

 in other specimens, e. g., those in Ell. N. Amer. Fung. no. 430, 

 the perithecia are smaller, about 95, « in diameter. In specimens 

 on Epigaea repens, in which the apical branching of the appen- 

 dages is the same as that of the plant on Vacciniiun, the perithecia 

 are frequently only 85 n in diameter. As regards the number of 

 the appendages, this is about 14 in Cooke & Peck's type, in 

 Ellis' specimen fewer (7 or 8), and on Epigaea frequently only 4 

 or 5. Nor is the small compact closely-branched apex of the ap- 

 pendages absolutely characteristic of the plant on Catalpa, as I 

 ha\^e seen just the same characters in a specimen on Vaccininm 

 (now in Kew Herbarium) sent to me by Professor Underwood. 

 The same, small, compact apex is also seen in the plant on Gay- 

 hissacia resinosa, which has been referred by all authors to AL 

 vaccinii. 



