Annual report of the North Carolina Agricultural Experiment Station . 14.—Ascochyta Chrysanthemi Stevens; portion of colony showing many pycnidia;cf. Fig. 13. VARIATION OF FUNGI DUE TO ENVIRONMENT. 61 of agar after the agar first plated had set, did not change the proportion ofthe two types. Nor did sowing in such way that the spores were at thebottom rather than at the top of the agar change results. There was amarked tendency of colonies of both types of the fungus to become moreproductive of large pycnidia where two different colonies approach each other,suggesting that there might be neede
Annual report of the North Carolina Agricultural Experiment Station . 14.—Ascochyta Chrysanthemi Stevens; portion of colony showing many pycnidia;cf. Fig. 13. VARIATION OF FUNGI DUE TO ENVIRONMENT. 61 of agar after the agar first plated had set, did not change the proportion ofthe two types. Nor did sowing in such way that the spores were at thebottom rather than at the top of the agar change results. There was amarked tendency of colonies of both types of the fungus to become moreproductive of large pycnidia where two different colonies approach each other,suggesting that there might be needed a co-operation of two diverse strainsin order to form a pycnidium ; that the strains of few pycnidia lacked therequisite individuals, and that the strains of many pycnidia had more thanone individual to the colony. To test this, colonies were traced from theearliest development, resulting in clear evidence that in some instances a colonydeveloped from a single spore was one with few pycnidia ; in other instancesa single spore produced a colony of many Fig. 15.—Coniothyrium Fuckelii Sacc.; portions of two colonies showing cir-cles of pycnidia near margins. Coniothyrium Fuckelii Sacc, from apple. In one instance this fungus, which rarely fruited, made pycnidia in almostperfect circles near the margins of each colony on the plate. (See Fig. 15.) These variations arc inexplicable and remind one of the mysterious changefrom ascigerons to non-ascigerous condition so frequently met in life-historywork with the imperfect fungi. Variability in Spore the beginning of mycology it has been customary to give sporemeasurements in specific description, probably originally with the idea of 02 THIRTY-SECOND ANNUAL REPORT, 1909. giving some information as to the approximate size of the plant concernedrather than to give exact descriptive limitations. With the advance of time,great importance has come to he attached to spore measurements—greater,perhaps, than
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