20 BASAL CELLS OF ACIDIA 
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 zxcidio- 
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 ecidia. On the spore- 
bed of the ecidium 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 
Fig. 21. Endophyllum Sempervivi. 
Formation of scidio-teleutospores © sterile (trichogyne) cell was 
(after Hoffmann). a, fusion-tissue; yot seen. 
b, basal cell ; c, intercalary cell; d, : 
spore; ¢, intercalary cell, degenera- Finally Fromme (1912) 
ting. found that in Melampsora Lini 
the spermogones and xcidia are produced simultaneously and 
only from infection by basidiospores. The spermatiophores 
ditfer 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 ecidia 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. Aicidiospores were observed with several 
nuclei, and one xcidiospore-mother-cell was seen with as many 
as eleven nuclei. (See also note on p. 29.) 
