298 Lang.—Development of Cycadean Sporangia . 
Theoretical Discussion of Results. 
In this and the preceding number of these studies, the 
development and structure of the microsporangium and ovule 
of Stangeria have been examined, so far as was possible on 
material obtained from cultivated plants. The general agree¬ 
ment of the results attained for this genus with those pre¬ 
viously recorded by Warming and Treub, renders a similarly 
detailed investigation of the remaining genera unnecessary. 
It therefore appears advisable to discuss briefly the general 
conclusions indicated by the facts in connexion with Stangeria 
and to reserve for a future number of these studies a com¬ 
parative treatment of the sporangia of the other Cycads; 
this will further enable the general view here advanced to 
be tested in detail. The equally important data supplied by 
the vegetative organs of the Cycadaceae, and the evidence 
regarding the phylogeny of the group obtainable from fossil 
plants, will also be most suitably considered after the series 
of existing genera has been comparatively treated. In this 
place the consideration of the general phylogenetic problem 
will be left on one side and only the morphology of the 
sporangia discussed. It is only necessary to point out here 
the justification, which the geological history of the seed¬ 
bearing plants affords, for considering the nature of the 
Cycadean ovule and its relation to the microsporangium, 
without extending the comparison to the other Gymnosperms 
or to the Angiosperms. So far as is at present known, 
Cycadean plants can be traced back to the Permo-Carboni¬ 
ferous flora. In rocks of this age well-preserved seeds are 
also found, some of which are probably Cycadean, while 
others may belong to the Cordaiteae. The remains of the 
latter group carry the first origin of the Cycadeo-Cordai- 
tean type of ovule to beyond the earliest period of which 
adequate fossils remains are preserved. It is unnecessary 
for our present purpose to consider the probable degree and 
kind of relationship between Cordaiteae and Cycadaceae. 
