. Bulletin (Pennsylvania Department of Forestry), no. 12-13. Forests and forestry. 25 i^ 24 All told, the Insects have very much more opportunity of obtaining pycnospores than ascospores, and it is not sur- prising that only a very few of the colonies of the chestnut blight fungus developing in the cultures originated from asco- spores (17). MICROSCOPIC EXAMINATION OF CENTRIFUGED SEDIMENTS. It has already been stated that, beginning with insect No. 34, the original wash water of those insects yielding positive results was centrifuged and given a thorough microscopic examination. The sediment h
. Bulletin (Pennsylvania Department of Forestry), no. 12-13. Forests and forestry. 25 i^ 24 All told, the Insects have very much more opportunity of obtaining pycnospores than ascospores, and it is not sur- prising that only a very few of the colonies of the chestnut blight fungus developing in the cultures originated from asco- spores (17). MICROSCOPIC EXAMINATION OF CENTRIFUGED SEDIMENTS. It has already been stated that, beginning with insect No. 34, the original wash water of those insects yielding positive results was centrifuged and given a thorough microscopic examination. The sediment had been concentrated in a very small quantity of water, and the entire sediment was generally examined. The purpose of the examination was primarily to ascertain whether the spores of Endothia parasitica carried were pycno- spores or ascospores, this to serve as a check on the observa- tions based on the rapidity of development of the colonies in cultures. It was possible to find pycnospores in the sediment from every insect which had yielded positive results in the cul- tures. Where these results were high, pycnospores were found very easily, but where the cultures indicated that only a few spores of the blight fungus were carried, they were located with greater difficulty, but could always be found after a reasonable search. The results of these examinations are presented in Table IV. It should be stated that the sediments were free from dirt particles, and that tlie pycnospores were therefore much easier to find than in the sediments from the birds (21), for a considerable amount of dirt was added to the bird sedi- ments as a result of scrubbing the feet, bill, tail, and wing feathers. Ascospores were found to be present in the sediments from only five insects, three of which were Leptostylus macula. It would seem reasonable to suppose that this insect would carry a considerable number of ascospores on account of its habit of eating the pustules, but such was not the case, f
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