rgrt] CHARLES—ANATOMY OF MARATTIA 85 
vascular tissues was found to be the safranin-anilin blue combina- 
tion. Early stages in the development of mucilage ducts came 
out better in Delafield’s hematoxylon and safranin. 
A clear conception of the course of the bundles can be gained 
rapidly by building up a clay model molded to match section by 
section. Though the proportions are not exact in this free-hand 
method, the relation of the bundles to each other is as accurate 
as in the wax models, and the saving of time is enormous. 
Investigation 
In the development of the stele of Marattia alata three stages 
stand out sharply: (1) the protostele; (2) the amphiphloic siphono- 
stele, or solenostele; and (3) the polycyclic dictyostele. The 
transitions from one stage to the next, because they are rapid and 
varying, are the points about which wide differences of opinion 
center. Of the two transitions, that from the protostele to the 
solenostele is the most variable among ferns. 
PROTOSTELE TO SOLENOSTELE 
In the Schizeaceae (BOODLE 1), the Cyatheaceae, and the Polypo- 
diaceae (GWYNNE-VAUGHAN 11), the first appearance of parenchyma 
in the protostele is at the periphery of the protostele at points just 
above the departure of leaf traces. The transformation works 
gradually inward. The internal parenchyma is therefore always in 
contact with the cortical parenchyma. In the Lindsaya type of 
stem and in Matonia (TANSLEY and LULHAM 27, 28) internal 
phloem is differentiated within the xylem and comes in contact with 
the peripheral phloem at the leaf gaps. In Pteris (LECLERC DU 
SABLON 19) a pith develops within the xylem. 
In Helminthostachys (LANG 18) the xylem, though sometimes 
solid, usually has parenchyma often conspicuous in the center, 
constituting a pith. Just below the origin of the first leaf trace 
the pith, if present, increases in size and is continuous with the 
parenchyma between the xylem of the leaf trace and that of the 
stele. If the stele is solid in the lower part of the internode, paren- 
chyma appears in the center of the xylem in preparation for the 
departure of the leaf trace. 
