404 Transactions. — Botany. 



Sections of the prothallia show little internal differentiation 

 of the tissues, certainly nothing which is comparable to that 

 described in L. complanatum and L. clavatum. The cells of 

 the tubercle appear of a rounded polygonal form. They show 

 scanty protoplasmic contents, and appear partly exhausted. 

 Those of the shaft are elongated ; on the surface they are rect- 

 angular, in the centre they tend to become longer and more 

 pointed. Starch is often abundantly present in the cells, 

 esnecially of the central part. An endophytic fungus may be 

 traced in the cells of the lower half of the prothallium. The 

 hyphae are exceedingly fine ; they have been traced passing 

 in through the rhizoids. Around the tubercle they often form 

 a close felt, which may pass below into a strand, which 

 suggests at first sight that the base of the tubercle passes into 

 a root. The tubercle is commonly brownish on the surface, 

 and the strand is a darker brown and almost opaque. But 

 sections show that it consists of fungus hyphaB. 



The prothallia are monoecious, and the archegonial necks 

 are a conspicuous feature on the crown. On a young pro- 

 thallium I have found two or three only, but on plants bearing 

 an embryo there may be from ten to twenty. They appear to 

 be formed in basipetal succession. In a young prothallium 

 they may be found on the summit of the crown, but in older 

 ones they seem to occupy a lateral position around about half 

 the circumference. The neck of the archegonium projects 

 from the surface of the crown as a hemisphere of colourless 

 cells, usually in two tiers of four cells each. The venter, with 

 the large oosphere, lies at a little depth below the surface. 

 The antheridia can scarcely be said to show in surface views, 

 as they lie sunk in the crown. Sections show that the 

 antheridial cavity is elongated at right angles to the neigh- 

 bouring surface. The cover-cells form a single layer. The 

 sexual organs would seem to resemble those of L. cermmm 

 more closely than those of other species of Lycopodium. 

 There are no multicellular paraphyses amongst the sexual 

 organs as in L. selago and L. phlegmaria, but on some parts 

 of the crown the surface-cells are slightly papillose. 



The thickness of the tissues renders it impossible to follow 

 the details of the early development of the embryo, except in 

 microtome sections. But it seems clear from the stages 

 which have so far been examined that the development at 

 first is much like that of the embryo in L. cermmm. The 

 embryo grows obliquely downwards and outwards ; the part 

 near the archegonial venter is the foot, at the opposite end 

 are formed the stem- apex and leaf. The first part of the 

 embryo to appear outside the prothallium is the tip of the 

 leaf ; it breaks out at a point on the side of the thicker part 

 of the prothallium, below the crown. A fissure extends thence 



