Proceedings of the American Academy of Arts and Sciences. VOL. XLVIII. No. 8.-OCTOBER, 1912. CONTRIBUTIONS FROM THE CRYPTOGAMIC LABORATORIES OF HARVARD UNIVERSITY. No. LXX-CULTURE STUDIES OF FUNGI PRODUCING BULBILS AND SIMILAR PROPAGATIVE BODIES. BY JOHN WILLIAM HOTSON. CONTRIBUTIONS FROM THE CRYPTOGAMIC LABORATORIES OF HARVARD UNIVERSITY. LXX. CULTURE STUDIES OF FUNGI PRODUCING BUL- BY JOHN WILLIAM HOTSON. THE term "bulbil" was first employed in connection with Fungi by Eidam in 1883 to designate certain sclerotium-like bodies, somewhat definite in form, and capable of reproducing the plant. They vary greatly in appearance, some consisting of a compact mass of homogeneous cells clearly distinguished from certain others which surround them. The latter form a single layer or in some cases several layers of cells, which may or may not become empty and colorless and which correspond, in a general way, to the pseudospores or accessory spores of certain smuts, while the cells which they surround are functional spores and capable of germination. Bulbils are the predominant type of reproduction in certain fungi, and in some cases the only means at present known. The most typical bodies of this nature are readily distinguished from sclerotia by their smaller size, more definite structure, and peculiar methods of development. There are other types, however, that seem to approach more nearly true sclerotia; while others again resemble very closely the "spore balls" of such forms as Tuburcinia, Urocystis, etc., among the Ustilaginales, or even the compound spores of such forms as Stemphylium, Mystrosporium, etc., among the Hyphomycetes; but from the first they are definitely distinguished by their method of germination, while in general they are readily separated from the last two by their mode of development. They thus seem to possess morphological characters that would place them in an intermediate position between sclerotia, on the one hand, and compound spores of the dictyosporic type on the other, with examples of transitional forms which grade into the former and others that are almost indistinguishable from the latter. Bulbiferous conditions among the fungi have, in general, been described under the following genera of the so-called "Fungi Imperfecti": Papulospora, Helicosporangium, Baryeidamia and Eidamia; but in a few instances, in which their association with other and more definite types has been reported, they have been included under the generic name applied to the latter as, for example, Dendryphium or Haplotrichum. There seems to be little or no uniformity or agreement among the writers on this subject, especially among the earlier ones, regarding the morphological significance of bulbils. Preuss, who was the first to describe bodies of this nature in 1851, considered each bulbil a single compound spore and placed the genus Papulospora, which he had created for their reception, in the "Bactridiaceae" of Corda, a family not now recognized, which was established to include fungi like Trichocladium Harz, bearing compound spores and with prostrate fertile hyphae. On the other hand, Karsten ('65) regarded the bulbil-like bodies which were associated with his "Helicosporangium" as an ascus-producing structure, which was included by him among the Erysipheae. Again, Eidam ('83) was of the opinion that the two genera, Papulospora and Helicosporangium, occupied an intermediate position between Ustilagineae and Erysipheae, while E. Fischer is inclined to place them among the Monascaceae. De Bary, in his "Morphology and Biology of Fungi," considers them briefly and includes them in a category which he calls "Doubtful Ascomycetes" and suggests that "the plants should be further investigated." In considering these forms at a later period, Harz ('90) included all structures of this nature then known under a new order, the "Leptoomycetes" and expressed the opinion that they are somewhat closely related to the Oomycetes and coordinate with them and the Zygomycetes. Inasmuch as these bulbils have received very little attention, our knowledge of their morphology, development, and taxonomy is very meagre. These forms are not as rare as has been generally supposed but are, on the contrary, widely distributed and of common occurrence. Substrata which have produced bulbils have been obtained from various parts of Canada and the United States; from Guatemala, Mexico, and West Indies; from South America and Europe. Their small size, the nature of the substratum on which they grow, and their failure to form a conspicuous fructification in a majority of cases, account to some extent for the fact that they are generally overlooked in the field and in laboratory cultures. The results of the present investigation emphasize the fact, more recently brought out by several mycologists, that these fungi do not belong to any one of the Natural Orders, nor do they in any sense form a group by themselves, but occur without regularity as imperfect |