Sexual Reproduction and the Organization of the Nucleus in Certain Mildews Volume 37 (Paperback)

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: in a fashion very difficult to show in even a large drawing. Drawing the successive cells as they appear in one plane, as I have done, results, for example, in causing the second cell of the ascogonium in fig. 27 to appear very short as compared with the first and third. As a matter of fact, however, the second cell is as large as the first, but bulges out on the lower side, as the section lies, so as to appear for the most part in the next section. From the outer cells of the perithecium in its basal region hyphae have begun to sprout, which form a sort of secondary mycelium comparable to the secondary mycelium of many Discomycetes (fig. 27). These hyphae grow out for a considerable distance and become interwoven with the mycelial hyphae over the stomata. Whether they give rise to internal hyphal branches with haustoria I have been unable to determine with certainty, as they are in no way differentiated from ordinary mycelial hyphae in appearance and their course is not easy to trace. There are good reasons, however, for doubting whether they ever pass through the stomata. The latter are crowded full, with all the entering branches which apparently can find room, long before the perithecia are sufficiently developed to give rise to these secondary hyphae. It seems likely that the latter serve merely for the better attachment and support of the developing perithecium. The single stalk-cells of the oogonium and antheridium together certainly seem hardly adequate, from a mechanical point of view, for giving a firm and safe support for the relatively immense fruit body developed on them. In a section such as that shown in fig. 30 the asci seem already to lie at approximately the same level in the ascocarp, and to be?for the most part, at least?in a horizontal layer slightly above ...