500 MOSSES AND FERNS CHAP. 



fied stem leaves, from which they readily separate when fully 

 grown. The axillary origin of the bulblets is only apparent; 

 they are really, so far as can be determined, similar in origin 

 to the ordinary branches, and formed without any relation to 

 the leaves. Before the bulblet becomes detached, the rudiment 

 of a root can be made out at the base, and as soon as it falls off 

 and comes in contact with the earth the root begins to grow and 

 fastens the bulblet to the ground (Fig. 289, C). The axis of 

 the bulblet, which at first is very short, rapidly elongates, and 

 the leaves formed up it have the characters of the ordinary 

 ones. As the leafy axis develops the fleshy leaves of the bulb- 

 let lose their chlorophyll completely and finally decay. 



Hegelmaier describes mucilage ducts in the stem and leaves 

 of L. inundatum and some other species, which are not unlike 

 those found in Angiopteris. 



The Sporangium 



The most recent and accurate account of the structure and 

 development of the sporangia of the Lycopodinese is that given 

 by Professor Bower in his memoir upon this subject (15). 

 His investigations include a number of species of Lycopodium, 

 and the following account is taken mainly from his memoir. 

 The results of his investigations show that there is much more 

 variety shown than was before supposed, both in the form of 

 the sporangium itself and in the mode of origin and number of 

 the archesporial cells. 



In L. selago the sporangium originates upon the upper 

 surface of the sporophyll close to its base, and in radial section 

 the young sporangium appears to originate from a single cell ; 

 but this is really only one of a transverse row of cells, all of 

 which participate in its formation. Each cell of this primary 

 row divides first into a large central cell (Fig. 290, C, .r) and 

 (in radial section) two peripheral ones. The central cell next 

 by successive periclinals forms a row of three cells, of which 

 the middle one is the archesporium, which, judging only from 

 radial sections, seems to consist only of a single cell ; but com- 

 paring with the radial section a tangential one, it is seen that 

 the archesporium really consists of a row of similar cells (Fig. 

 290, F). The growth in the upper part of the sporangium is 

 stronger than below, so that a distinct, although short stalk is 



