404 MOSSES 



planes of the apical cell. Each segment (c and o, seg. c) 

 immediately after its separation divides and subdivides, pro- 

 ducing a mass of cells from which a projection grows out 

 forming a leaf, and in this way the stem increases in length 

 and the leaves in number. 



Asexual reproduction takes place in various ways ; all of 

 them are, however, varieties of budding, and the buds always 

 arise in the form of a linear aggregate of cells called a 

 protonema ; from this the moss-plant develops in the same 

 way as from the protonema arising from a spore (p. 408). 



The gonads are developed at the extremity of the main 

 stem or one of its branches, and are enclosed in an involucre 

 or tuft of leaves often of a reddish colour the terminal bud 

 of the fertile shoot or so-called " flower " of the moss. 



The spermary (Fig. 109, A 1 , A 2 ) is an elongated club- 

 shaped body consisting of a solid mass of cells, the outer- 

 most of which form the wall of the organ, while the inner 

 (A 3 ) become converted into sperms. The latter (A 4 ) are 

 spirally coiled and provided with two cilia : they are liber- 

 ated by the rupture of the wall of the spermary at its 

 distal end (A 2 ), and swim in the rain or dew covering the 

 plant. 



The ovaries a (see Preface, p. viii) (B 1 , B 2 ) may or may 

 not occur on the same plant as the spermaries, some 

 mosses being -moncecious, others dioecious. Like the sperm- 

 aries, they consist at first of a solid mass of cells which 

 assumes the form of a flask, having a rounded basal portion 

 or venter (v) and a long neck (n). The outer layer of cells 

 in the neck and the two outer layers in the venter form the 

 wall of the ovary, the internal cells are arranged in a single 



1 The ovary of mosses, ferns, &c., is usually called an archegonium : 

 the spermary, as in the lower plants, an antheridium. 



