287 
of Lycopodium clavatum , L. 
distinguishable from the section across the lateral margin 
(Fig. 8). So far therefore as the evidence afforded by these 
specimens goes, the archegonia and antheridia appear to be 
formed in regular succession following the marginal growth of 
rothalli. 
.The antheridium is developed from a single superficial cell 
which divides by a wall parallel to the surface (Fig. 10). In 
the outer of the resulting cells only anticlinal divisions occur, 
the free wall of the antheridium being only a single layer of 
cells in thickness ; from the inner by repeated divisions the 
small-celled tissue, which gives rise to the spermatozoids, is 
formed (Figs. 11 and 12 ). The mature antheridium projects 
very little if at all from the surface of the prothallus. The 
large ellipsoidal mass of spermatocytes is wholly enclosed 
within the generative layer of the latter ; its form and size will 
be evident from Figs. 13 and 14, which represent longitudinal 
and transverse sections of almost mature antheridia. The 
cells adjoining the spermatocytes are usually more or less 
flattened, but do not present any distinctive characters. The 
development of the spermatozoids resembles that in other 
Vascular Cryptogams, but was not followed in detail. The 
opening of the antheridium appears to be effected by the 
breaking down of a small cap-cell, which, with the cells 
surrounding it originates from the outer of the two segments 
into which the mother-cell of the antheridium divides. A 
sufficient number of sections in the required direction were 
not available to determine the succession of divisions in this 
cell, but, as the examples figured (Figs. 15 and 16) show, 
there is probably some variation in this respect. The sperma- 
tozoids were not obtained. 
The archegonium also is developed from a single superficial 
cell which divides by two periclinal walls into a series of three, 
which are recognizable by their dense protoplasmic contents 
(Fig. 17.) From the outer of these the neck arises ; the other 
two form the central series of cells. A basal cell does not 
appear to be present. Older stages, in which the neck as yet 
projects but little above the surface, are shown in Figs. 18 and 
