20 



ISASAL CELLS ()!•' .ECIDIA 



Again, in l!»l I, Hoffmann invest igated a l T rodine of a lower 



t\ |»- i li; iusi of i hose |)i-e\ iously considered, \ i/. tindophyllum 



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 aecidia. 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 aecidia 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 aecidia 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 secidiospore-mother-cell was seen with as many 

 as eleven nuclei. (See also note on p. 29.) 



Fig. 21. Endophyllum S< mpervivi. 



Formation of aaeiciio-teleutospores 

 (after Hoffmann), a, fusion-tissue; 

 /;, basal cell ; e, intercalary cell ; d, 

 spore; e, intercalary cell, degenera- 

 ting. 



