GROUP I. THALLOPHYTA : FUNGI : ASCOMYCETES. 297 



The sterigmata are borne in receptacles termed spermogonia. 

 The spermogonium consists of a wall formed of coherent hyphae 

 from which a number of free hyphse, the sterigmata, grow into 

 the interior and produce, by repeated abstriction at their apices, 

 a number of small rod-shaped cells, the spermatia, with a cell- 

 wall, which seem, in some cases, to be the male cells (see p. 277). 

 These cells reach the surface through the small opening of the 

 spermogonium. 



Whilst it is true that, in very many cases, the spermatia germinate like 

 gonidia, this does not absolutely prove that they may not be imperfect or de- 

 generate sexual cells ; the independent germination of undoubted male cells is 

 not uncommon in the Algae (p. 226). 



A process of fertilisation has not been observed in all forms in 

 which sexual organs are present ; but it has been observed in the 



c. 



FIG. 206. Sexual reproduction of Eremascus albus. A Sexual orpan.s in contact. B 

 Fusion of the organs at the apex, with developing ascocarp. C Mature ascocarp, consisting 

 of a single ascus containing eight ascospores. (x 1000 : after Kidam.) 



following cases which are representative of the various modes in 

 which it may take place. 



In Eremascus (Fig. 206) the apices of the undifferentiated 

 sexual organs come into contact, and, the cell-walls being absorbed 

 at the point of contact, the protoplasmic contents fuse. 



In Pyronema the trichogyne conies into close contact with an 

 adjacent pollinodium ; the cell-walls become absorbed at the point 

 where the apex of the trichogyne presses against the pollinodium, 

 and the contents of the two organs fuse (Fig. 207). 



In Collema (Fig. 208) it appears that the spermatia are brought, 

 by means of water, into contact with the projecting trichogyne ; 

 one of them adheres to the trichogyne ; the cell- walls are absorbed 

 at the point of contact, and the protoplasm of the spermatium 

 enters the trichogyne. 



It is probable that, in consequence of sexual degeneration, the 



