. The British rust fungi (Uredinales) their biology and classification. Rust fungi. 20 BASAL CELLS OF ^CIDIA Again, in 1911, Hoffmann investigated a Uredine of a lower type than most of those previously considered, viz. Endophyllum Sempervivi. This genus differs from all the other Uredinales in its mode of development. It has only spermatia and secidio- spores, the latter functioning also as teleutospores in that their conjugate nuclei fuse, and then on germination they produce a basidium and basidiospores. These basidiospores reinfect the host and produce both spermogones and secidia. On the
. The British rust fungi (Uredinales) their biology and classification. Rust fungi. 20 BASAL CELLS OF ^CIDIA Again, in 1911, Hoffmann investigated a Uredine of a lower type than most of those previously considered, viz. Endophyllum Sempervivi. This genus differs from all the other Uredinales in its mode of development. It has only spermatia and secidio- spores, the latter functioning also as teleutospores in that their conjugate nuclei fuse, and then on germination they produce a basidium and basidiospores. These basidiospores reinfect the host and produce both spermogones and secidia. On the spore- bed of the secidium two ad- jacent cells unite by the disso- lution of the intervening walls (Fig. 21); first a small hole is formed, which grows larger until at last almost no trace of the wall is left. The disap- pearing wall is often horizontal, not vertical as in most of the other cases,and the conjugating cells are not situated in any definite plane. In such cases a sterile (trichogyne) cell was not seen. Finally Fromme (1912) found that in Melampsora Lini the spermogones and secidia are produced simultaneously and only from infection by basidiospores. The spermatiophores differ from all others described in being many-celled, each cell producing a single spermatium on a sterigma-like process; they arise from a regular layer of large rectangular cells at the base of the spermogone. The secidia are stated to be undistinguish- able from the spermogones externally, but produce female gametes in the usual way, generally with one or two •' buffer " cells which speedily disintegrate. The female gametes conju- gate, in abundance, laterally in pairs, often in threes or fours; the fusing cells are of equal rank, but need not be in the same horizontal level. iEcidiospores were observed with several nuclei, and one aecidiospore-mother-cell was seen with as many as eleven nuclei. (See also note on p. 29.). Fig. 21. Endophyllum Sempervivi. Formation of ffioidio-teleutospor
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