A Vascular Sporangium. 65 
whole surprising in the case of fossil Ferns, for these tracheae are 
very delicate structures and liable to obliteration on the maturing 
of the sporangium. In the fossil seeds of Gymnosperms— Stephan- 
ospermum , and others—the presence of tracheal elements at the 
periphery of the nucellus of the seed, passing from the chalaza to 
the pollen-chamber, was a common feature. Not improbably, in 
these cases, adequate physiological requirements connected with 
important functions were operative and led to the retention of the 
tracheal tissue to a late stage in development. 
The presence of vascular tissue in close proximity to the 
sporangium in Pteridophytes generally is not very common. In the 
sporangiophore of Sphenophyllum Daivsoni a small bundle runs to a 
point just short of the sporangium, where it ends in a somewhat 
bulb-like enlargement consisting of reticulated tracheides. Some¬ 
thing of the same kind is indicated in HehninthostacJiys and 
Botrychium , and occasionally in Lygodium, 1 whilst in Tmesipteris 
little bundles run within the margin of the synangial septum. 
Amongst the Cycads I find that strands of well-developed spindle- 
shaped tracheides penetrate the pedicels of the pollen-sacs in 
Boweuia spectabilis 3 , where they may be found reaching up to within 
a distance of six cells of the actual sporogenous mass. To these 
instances may be added that of the pollen-sacs in Cordaianthus 
Penjoni and C. Sapoytanus , to the base of which delicate vascular 
ramifications penetrate 3 . Finally, presenting some analogy with the 
foregoing we have certain instances amongst the Amentales 4 — 
Casuay 'uia , Castanea and Corylus —in which spindle-shaped tracheides 
occur right amongst the sporogenous tissue of the nucellus, though 
in a manner suggesting that they are vestigial in nature. 5 
But the chief interest in the observation here put on record 
seems to lie in the recognition in a sporangium of one of the 
palaeozoic Ferns of a condition which is recognised as normal in so 
many of the fossil gymnosperm seeds. If my conjecture that the 
sporangium belong to one of the Botryopterideae be confirmed, 
1 Scott, loc. cit., p. 2S9. 
2 I am indebted to my friend Mr. A. C. Seward, F.R.S., for kindly 
placing at my disposal a series of sections through a cluster of 
pollen-sacs of this plant. 
3 Cf. Renault—Structure compare de quelques tiges de la Flore 
Carbouifere. PI. xvi , fig. 14, g, and PI. xvii., fig. 3, /. 
4 M. Treub, in Ann. du jard, bot. de Buitenzorg, vol. x. M. Henson, 
«• Contrib. to the Phn bryology of the Amentiferae.” Trans. 
Linn., Soc. 2nd ser., vol. iii , Bot. S Nawascliin, Bull, de l’Acad, 
Imp. des Sc. de St. Petersbourg, 1899, vol. x., No. 4, p. 375. 
*M. Benson, loc. cit., p. 421. 
