486 MOSSES AND FERNS CHAP. 



described for Phylloglossum. The first investigator who suc- 

 ceeded in obtaining the germination of the spores was De Bary 

 (i), who studied the earliest stages in the germination in L. 

 inundatum, but was unable to obtain the later ones. About 

 fifteen years later Fankhauser found the old prothallia of L. 

 annotinum (i), but our first complete knowledge of the pro- 

 thallium and embryo is due to the labours of Treub (2), who 

 examined most thoroughly several tropical species of Lyco- 

 podium. Goebel (18) succeeded in finding a number of pro- 

 thallia of L. inundatum which correspond very closely to L. 

 cernuum, the first species examined by Treub. Other Euro- 

 pean species have more recently been investigated by Bruch- 

 mann ( 5 ) and Lang ( i ) . 



The germination of the spores in L. cernuum and L. in- 

 undatum is much like that of the homosporous eusporangiate 

 Ferns. The tetrahedral spores contain no chlorophyll, but it 

 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 ap- 

 pears to normally remain undivided. The other enlarges and 

 becomes divided by an oblique wall (Fig. 283, A), and func- 

 tions 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 germination of L. cernuum corresponds 

 exactly with De Bary's observations upon L. inundatum. The 

 ovoid body formed at first Treub calls the "primary tubercle/' 

 and this does not develop directly into the complete prothal- 

 lium, 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. 283, B). The base 

 of this filamentous appendage, however, later develops longi- 

 tudinal 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 suc- 

 cession, and the growth may be considered, in a general way 

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



