269 
A rchangiopteris Henryi and other Marattiaceae. 
In the stem, nor as regards the primitive vascular arrangement in the 
petiole. At the same time the Marattiales possess a number of distinctive 
anatomical features of considerable value; such as (1) the centrifugal 
differentiation of the protophloem, (2) the exceptional nature of the internal 
vascular strands in the petiole, (3) the special method by which the petiolar 
branches are supplied with vascular tissue, and (4) the fact that roots arise 
upon the internal strands in the stem. The first of these characters is quite 
without parallel in either the Ophioglossales or the Filicales. It is true that 
a centrifugal development has been observed in the phloem of Todea by 
Seward and Ford 1 ; I have also seen the same thing in Osmunda regalis , 
where it is quite clear that the so-called protophloem is still undifferentiated 
when the sieve-tubes of the rest of the phloem lying within it are fully 
formed. But this state of affairs is not really comparable with that in the 
Marattiaceae, because the ‘ protophloem ’ in the Osmundaceae is clearly 
derived from the same layer of meristematic cells which also gives rise 
to the pericycle ; and further, its elements, even when mature, are not verti- 
cally elongated like sieve-tubes, but tangentially, like the cells of the 
pericycle. In fact these elements may be regarded as specialized inner 
layers of the pericycle, and it may be said that the Osmundaceae have 
no true protophloem at all. Again, in the phloem of Aneimia and Schizaea 
there is no clear distinction into protophloem and metaphloem, but all the 
sieve-tubes remain functional throughout ; in this case, however, the whole 
phloem has more the appearance of protophloem than of metaphloem. In 
relation to this it is suggestive to note that Boodle 2 is of the opinion that 
in Schizaea digitata , the whole of the phloem is derived from the same 
meristematic layer that also gives rise to the pericycle and endodermis. 
From some observations that I made on Aneimia hirta it appears that the 
same view holds good for this plant also. It is, indeed, hardly possible 
at present to decide upon the proper morphological value to be given 
to these differences in the constitution of the phloem, but at the same time 
the unique position of the protophloem in the Marattiaceae seems to me to 
be of so great importance that, until some idea of its real meaning has been 
obtained, the other anatomical evidence cannot with advantage be brought 
to bear upon the question of the relationship of the order. 
The sori and sporangia on the one fertile leaf of the specimen were 
examined by Professor Bower, who permits me to add the following 
account. 
‘ The sporangia correspond very closely to those of Angiopteris ; they 
are somewhat more elongated and pointed. Cut transversely, they show 
the same differentiation of the three- to four-layered wall. Comparing my 
1 ‘ The Anatomy of Todea,’ &c., Trans. Linn. Soc., 2nd Series, vol. vi, p. 23 7, 1903. 
2 c Comparative Anatomy of the Hymenophyllaceae/ & c., Annals of Botany, vol. xiv, No. Iviii, 
p. 377, 1901. 
