5°8 
Tansley and Lulham. — A Study of the 
In the case which we have been able to trace out most fully (Text- 
Fig. 1 5), the behaviour of the dorsal protoxylem of the second cylinder is as 
follows. The single dorsal protoxylem-strand of the second cylinder branches 
into two, right and left (Text-Fig. 15, B). Each of these then again divides 
into a dorsal and ventral branch (Text-Fig. 15, c). The dorsal branches 
continue straight forward in the compensation-tongue, which eventually 
fills up the gap in the outer stele (d-g), while the ventral branches each 
send off a strand which runs straight up and divides into two, an outer and 
an inner division, of which the former enters the ‘ gutter/ i. e. the continua- 
tion forwards of the final curl (outer limb) of the lateral loop of the leaf- 
trace, while the latter enters the inner limb (d and E, F and G). From 
this point these two last-mentioned strands on each side run backwards 
and upwards into the trace, while the original ventral strands run on 
forwards in the free edges of the gap in the second cylinder (f, G, h). 
A comparison of other cases shows an essentially similar condition of 
things. Sometimes the protoxylems supplying the lateral loops are in 
direct connexion, not only with those running in the free edges of the 
gap of the second cylinder, but also with those belonging to the compensa- 
tion-strand which closes the gap in the outer cylinder. In any case the 
important point is that the protoxylem as well as the metaxylem supply 
of the lateral loops of the leaf-trace runs backwards and upwards from 
xylem belonging to the second cylinder. 
The Nature and Phylogenetic Relations of the 
Vascular System in Matonia. 
Morphological Position and Origin of the Matonia- type. 
The first general result obtainable from the foregoing observations is 
the apparently definite solution of the problem of the nature and origin 
of the internal vascular cylinders in the rhizome of the adult Matonia 
pectinata , and that in the sense already indicated by Gwynne-Vaughan 1 . 
On the basis of a series of cases represented by Dicksonia apiifolia , 
D. adiantoides , D. rubiginosa , and Pteris elata , var. Karsteniana , Gwynne- 
Vaughan concludes that the internal vascular cylinder in the last-named 
plant has arisen as the result of progressive elaboration from a local 
thickening of the margin of the leaf-gap of the original solenostele. He 
further concludes that the vascular system of Matonia pectinata is 
* essentially similar.’ The detailed account we have given of the origin 
of the internal cylinders in the young plants of Matonia and in the weak 
1 Gwynne-Vaughan (’ 03 ), pp. 703-5. The suggestions of Seward (’ 99 , p. 180) and Boodle (’01 B, 
p. 739) as to the splitting off of an internal ring from the original solenostele must be dismissed as 
untenable. 
