v. MOSSES (MUSCI): SPHAGNALESANDRE&ALES 187 



mother cell. The number of the latter is very small, seldom 

 exceeding five or six. They become rounded off, and gradu- 

 ally displace the other endothecial cells, which doubtless serve 

 as a sort of tapetum for the nourishment of the growing spores. 

 Each spore mother cell as usual gives rise to four spores, which 

 are very much larger than in any other Moss. A section of 

 the ripe sporogonium (Fig. 96), shows that only one of the 

 primary three layers of amphithecial cells can be recognised 

 except at the extreme apex and base. No seta is present, and 

 a foot much like that of Andrecca, and penetrating into the tis- 

 sue of the stem apex, is seen. 



Leitgeb is inclined to look upon Archidium as a primitive 

 form allied on the one hand to Andrecea and on the other to 

 the Hepaticae, possibly Notothylas. However, as his assump- 

 tion that the latter has no primary columella has been shown to 

 be erroneous, his comparison of the whole endothecium of Ar- 

 chidium with that of Notothylas cannot be maintained, as we 

 have shown that in the latter, as in Anthoceros, the arche- 

 sporium arises from the amphithecium, and not from the en- 

 dothecium, as is the case in Archidium. Inasmuch as the game- 

 tophyte and sexual organs of Archidium are those of the typical 

 Mosses, it seems quite as likely that the older view that Ar- 

 chidium is a degenerate form is correct. At any rate, until 

 more convincing evidence can be brought forward in support 

 of a direct connection between it and the Hepaticae than the 

 formation of the spores directly from the central tissue of the 

 sporogonium, it cannot be said that the question of its real affin- 

 ities is settled. 



