Annual report of the North Carolina Agricultural Experiment Station . sulting in naked spores; it may cause failure todevelop color; it may limit the size of the colony; or it may be without effect. There are many paired species of the imperfect fungi agreeing closely, ex-cept in the presence or absence of one character. These pairs often occur VARIATION OF FUNGI DUE TO ENVIRONMENT. 51 upon tbe same host, e. g., &&ptoria lycopersici Speg. and a Cylindrosporiumon tbe tomato, and CyUndros pari urn Chrysanthemi E. & D. and SeptoriaChrysanthemi Cav. on the cultivated Many other ins
Annual report of the North Carolina Agricultural Experiment Station . sulting in naked spores; it may cause failure todevelop color; it may limit the size of the colony; or it may be without effect. There are many paired species of the imperfect fungi agreeing closely, ex-cept in the presence or absence of one character. These pairs often occur VARIATION OF FUNGI DUE TO ENVIRONMENT. 51 upon tbe same host, e. g., &&ptoria lycopersici Speg. and a Cylindrosporiumon tbe tomato, and CyUndros pari urn Chrysanthemi E. & D. and SeptoriaChrysanthemi Cav. on the cultivated Many other instances could be cited. The lack of fixity of such a structure as even the pycnidum throws doubtupon the validity of. such species as these and indicates the necessity of closecomparative study. II. Density of Mycelium : Zone formation of concentric zones is by many fungi one of the most conspic-uous characters shown in cultures. These zones may be due to any one ofmany structural characters of the colony; to varying density of spore niass-. Fig. 6.—Ascochijta Chri/satithcmi Stevens; plate culture showing that theformation of zones is not coincident with diurnal changes; ink marks showgrowth for three consecutive days. ing; pycnidia grouping, mycelial branching, color, etc. It is a frequent pre-nomenon in nature in the fairy rings of the toad stools, the concentric mark-ings of many loaf spots, fruit rots, etc. These effects have been attributed to Woonixo, Diseases of cultivated chrvsanthemums, Malpighia 15 (1902), 329-341. E. S. ,777. iHALSTKi), Chrysanthemum leaf spot, American Florist, 10 (1894), No. 333, 263. E. S. R. 6,311. Beach, Leaf spot of chrysanthemum, N. Y. State Sta. Rpt., 1892, 557-560. Halsted, Report of fungus disease of plants, X. J. Sta. Rpt., 1S91, 233-340. •Sacc. Syll. Fung. 11, 542, Xos. 3497, 3 19S, 3757. Tuheuf and Smith, Diseases of Plants, U. S. Dept. Agr., 1906, 507. Geneva Sta. Rpt., 14, 529. X. J. Sta. Rpt., 1894,
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