546 Worsdell. — Observations on the Vascular 
appendages in all the groups are in structure, as a rule, similar to 
those of the foliage-leaves. Sometimes they exhibit characters 
rather more ancient than obtain in the latter. A notable 
instance of this occurs in the bundles of the sterile bracts or 
sporophylls of the rudimentary cone of Taxus , where, contrary 
to what we know to be the case in the foliage-leaves, a large 
amount of centripetal xylem is found. 
That ancestral characters should turn up in preponderating 
measure in those organs which are intimately associated with 
the most primitive parts of a plant, viz., the reproductive 
organs, is what one would naturally expect. Hence the 
mesarch structure of the bundles of the sterile bracts or 
sporophylls of Taxus. But the most ancient characters would 
surely be expected to be found in the actual reproductive 
organs themselves. In my recent paper on the sporophylls 
of Cycads 1 I made a special point of remarking and figuring 
the concentric structure (which I regard as ancestral) of many 
of the bundles which directly supply the megasporangia in 
most of the genera. While in the other parts of the sporophyll 
the bundles were nearly always of the collateral type of 
structure, in every case some of those which were sectioned 
immediately below the insertion of the sporangium 2 , and 
some of those (and this is the most important point) in the 
integument of the sporangium, exhibited in unequivocal form 
a more or less complete concentric type of structure. Now, 
as has been described in the foregoing pages, bundles exhibit- 
ing a concentric type of structure occur in the seminiferous 
scale (the vegetatively-developed outer integument , according 
to Celakovsky’s view) of Araucaria , Pinus , and Sciadopitys. 
No doubt, if further investigations had been made, they would 
have been found in the other genera also. The bundles 
exhibiting this structure are usually those in closest connexion 
with the sporangium, the others exhibit the ordinary collateral 
structure. 
1 Worsdell : ‘The Vascular Structure of the Sporophylls of the Cycadaceae;’ 
Ann. Bot. Vol. XII, 1898. 
2 loc. cit., Figs. 4 and 20. 
