28 o 
Notes. 
genera a plurality of sporangia is the normal condition, and the 
closeness of relation of these organisms to the true Lycopods is open 
to question. The importance of a morphological character for 
comparative purposes depends on its constancy ; and on this ground 
the solitary, leaf-subtended sporangium of Lycopodium may be held 
as a character of high morphological value ; it stamps this series of 
Pteridophytes as peculiar from all others. 
But it is not necessary that the simple type should always be strictly 
maintained; few characters in the whole series of plants are more 
stereotyped than the structure of the Bryophyte sporogonium ; yet 
branched, two-headed sporogonia are occasionally found. The causes 
of this are obscure ; probably nutritive conditions have close con- 
nexion with it. It is with such cases of plural development of parts 
normally single that I should rank this plurality of sporangia in 
lycopodium rigidum . 
On the other hand, it has lately been shown by Solms-Laubach 
(Bot. Zeit., 1902) that Isoetes, which has usually a simple axis, is 
occasionally branched ; in this we may see a fresh indication of its 
Lycopodinous affinity, where dichotomy is common. The case is 
somewhat the same in Phylloglossum, where also, though the plant 
is normally unbranched, occasional dichotomies occur. These 
branchings seem rather reminiscent of a feature common in the 
main groups to which these plants belong, than to be actually new 
developments. 
But the case of the plural sporangia in Lycopodium rigidum I should 
regard as a new development; it probably arose by a separation 
of the sporogenous group of a normal sporangium into two : on 
this point, however, it is impossible to go beyond mere conjecture, 
since the case is isolated and observed only in the mature condition. 
I do not think it will be wise to attach high importance to this 
abnormality for purposes of comparative argument, beyond recog- 
nizing that it shows how even the most rigid facts of morphological 
experience are liable to exception, and that this applies equally to 
spore-bearing members, in cases where their forms seem most 
stereotyped. 
Glasgow, 
October , 1902. 
F. O. BOWER. 
