ON THE DEVELOPMENT AND STRUCTURE OF MOSSES. 19 



a strange analogy to similar organs in Balanophorce, vary 

 somewhat in form. The resemblance however is more appa- 

 rent than real, and is confined to certain species of Balano- 

 phorce without extending to the whole group. In Bryum they 

 are simply filiform ; in Mniam the upper cells are much larger, 

 and so contracted at the commissures as to constitute a moni- 

 liform thread; in Polytrichum they are spathulate and divided 

 above, both transversely and vertically, by numerous cells. 

 In Diphyscium they present a curious object under the micro- 

 scope, the outer membrane of each constituent cell bursting 

 in the midst, so that each commissure has a little cylindrical 

 sheath attached to it, contracted in the middle, and open both 

 above and below. 



/. The female organs are far more complicated in their 

 structure, and are disposed in little special offsets from the 

 stem, or at its tip. Two parts have been distinguished in the 

 floral bud, if it may be so called, the ' perigynium/ which con- 

 sists of leaves encircling the true bud, and the ' perigamium/ 

 the portion which contains the fruit; but these distinctions 

 are of little consequence. I shall have occasion to speak of 

 what is called the ' perichsetium ' afterwards. 



In an early stage of growth, the female fruit, or ' archegon/ 

 consists first of a single cell, then of an oblong cellular mass, 

 closed above and without any central cavity. As, however, 

 cell-division proceeds, the cells recede from the centre, and 

 leave a linear channel, at the base of which, in a slijfnt dilata- 

 tion, is seated a single cell fixed below and free above, which 

 ultimately gives rise to the sporangium. The archegon, when 

 fully formed, is flask-shaped and perfectly free above, with a 

 long neck arid an evidently cellular structure, the central 

 channel being visible through the walls (Plate 1, fig. 2). The 

 cells at the top of the archegon become loose and detached 



c 2 



