400 
MARSILIACE^. 
invariably takes place at a fixed spot, which may be pointed out 
before germination has commenced. It is at that part of the 
sporule indicated by the three radiating lines which appear to 
have been produced by the pressure of the three other sporules 
that originally helped to constitute the quaternary union ; and 
as the spores of all the other tribes appear, according to Mohl, 
to be developed in similar unions, it is most probable that simi- 
lar lines indicating a valvular dehiscence also exist on them. 
This is certainly the case in some mosses, for instance, in CEdi- 
podium, and in Isoetes, Lycopodimn^ and Osmunda regalis ; 
and in those instances where such a structure is not visible, it is 
probably owing to a thickening of the membrane, or a deposi- 
tion of opaque matter on its surface, as in Pilularia. In the 
mature sporules of Pilularia they can only be discovered by 
dissection, and in the abortive ones they cannot be discovered 
at all after the first stages of their growth ; whilst, again, the 
sporules of Jungermannia complanata exhibit similar lines after 
they have been submitted to the action of sulphuric acid. After 
the protrusion of the germ, however, it does appear to be quite 
immaterial from what part of the germ the first leaves, root or 
stem shall arise.” 
The ^History of British Ferns’ ends here : the subsequent pa- 
ges are almost entirely confined to extracts, which the author 
either considered too voluminous for foot-notes or accidentally 
overlooked : he trusts they will not be found wholly devoid of 
interest and utility. And now, gentle reader, the author takes 
his leave, hoping that when perusing his performance, when de- 
tecting occasional errors — and doubtless such there are — thou 
wilt make that kind and generou^ allowance which we should all 
accord to the endeavour to do well. 
