So Sykes . — The Anato?ny and Morphology of Tmesipteris. 
question is whether the synangium is the homologue of one sporangium or 
of several. Bower’s account of the development of the sporangium in 
Tmesipteris supports the view that it is derived from a single sporangial 
mass by septation. The tissue of the septum has an origin quite similar to 
that of the sporogenous tissue, and in abnormally simple forms the septum 
may be aborted, and the tissue which would have given rise to it may form 
a tapetum or even give rise to spores. The septation of a sporangium is 
by no means an unusual phenomenon, for example the anthers of some 
Onagraceae 1 may be mentioned here. In the Lycopodiaceous series the 
trabeculae of Isoetes and Lepidodendron suggest incomplete septation. At 
first sight the reception of two bundles by the synangium in Tmesipteris 
may appear to imply the separate origin of the lobes ; but this is not 
a necessary conclusion, on the contrary the large masses of developing 
spores so obviously require a plentiful supply of food and water that the 
branching of the sporangial trace would seem a very likely occurrence. 
On the other hand Bower 2 found that a study of the development of 
the sporogenous masses in Psilotum showed each to be referable to a single 
parent cell. This state of affairs was not proved in Tmesipteris , but, as far 
as it goes, it supports the view of the separate origin of each lobe of the 
synangium, and their subsequent fusion. As far as comparative morphology 
is concerned there is little of a positive nature to support either view. 
Bower holds that the synangium is derived from an originally simple 
sporangium like that of a Lycopod, but present opinion appears to incline 
more to the view that the Lycopodiales are reduced rather than primitive ; 
and it is therefore possible that their sporangium is to be looked upon as 
formed by the ultimate fusion of such a group of sporangia as we find 
partially fused in Tmesipteris. In the Calamites, in Cheirostrobus and in 
Sphenophyllum , there is generally more than one sporangium borne by a 
sporophyll, and Sphenophyllum majusp with its tuft of four sessile sporangia, 
bears a most striking resemblance to Tmesipteris. If the comparative evidence 
is to be considered as of any value, it seems to lend support to the view 
that the synangium was originally formed by the fusion of separate 
sporangia, but it appears to me very difficult to come to any definite 
conclusion on the matter. 
It is otherwise, however, with the theories concerning the morphology 
of the whole sporophyll. 
On this question there have been for some time two principal views. 
Mettenius, Luerrsen, Celakovsky, Solms Laubach, Dangeard, Bower, Scott, 
and Thomas have believed the ‘ sporophyll ’ to be a foliar organ ; whilst 
Juranyi, Strasburger, Goebel, Sachs, and Bertrand have supposed it to be 
a fertile branch, the first two leaves of which have the appearance of 
1 Bovver, 1896, p. 5. 
2 Bovver, l.c., 1894. 
Scott, 1907, p. 152, Fig. 3. 
