464 3I0SSES AND FERNS chap. 



prothallia of L. annotinuin} but our principal knowledge of the 

 prothallium and embryo is due to the labours of Treub,^ 

 who has most thoroughly examined several tropical species of 

 Lycopodiuin. Goebel ^ succeeded in finding a number of pro- 

 thallia of L. innndatum which corresponds very closely to L. 

 cernimni, the first species examined by Treub. 



The germination of the spores is much like that of the 

 homosporous eusporangiate Ferns. The tetrahedral spores con- 

 tain no chlorophyll, but this develops before the first division 

 wall is formed. This may be either vertical or horizontal, or 

 more or less inclined. The two primary cells are nearly equal 

 in size, but one of them appears to normally remain undivided. 

 The other enlarges and becomes divided by an oblique wall 

 (Fig. 244, A), and functions for some time as an apical cell, 

 from which segments are cut off alternately right and left. 

 Usually each segment is then divided by a periclinal wall into 

 a central and a peripheral cell. Up to this point the germina- 

 tion of L. cernuuni corresponds exactly with De Bary's obser- 

 vations upon L. inundatmn. The ovoid body formed at first 

 Treub calls the " primary tubercle," and this does not develop 

 directly into the complete prothallium, but the apical cell ceases 

 to form two rows of segments and elongates so as to produce a 

 filament in which for a time only transverse walls are formed 

 (Fig. 244, B). The base of this filamentous appendage, how- ' 

 ever, later develops longitudinal walls and forms a thickened 

 cylindrical mass, which is the beginning of the prothallium body. 

 Sometimes, but not usually, a second filamentous outgrowth is 

 formed from the primary tubercle, which may produce a second 

 prothallial body. 



The growth of the prothallium proper does not seem to 

 show a definite meristem, but at the summit are produced a 

 number of leaf- like lobes which seem to arise in acropetal 

 succession, and the growth may be considered, in a general 

 way at least, as apical. The individual lobes are usually two 

 cells thick, and like those of Equisetmn show a definite two- 

 sided apical cell. This apical growth later disappears and all 

 trace of it is lost in the older lobes. Root-hairs are produced 

 only in small numbers from the cylindrical prothallium body, 

 and are usually entirely absent from the primary tubercle, whose 

 peripheral cells are always occupied by an endophytic fungus 

 1 Fankhauser (i). ^ Xreub, M. (2). ^ Goebel (18). 



