5 Bo Davey. —Seed ling Anatomy of certain Amentiferae. 
plumular strands in the intercotyledonary plane becomes divided and 
united to the cotyledonary phloem in the diagonal corners. A few xylem 
elements from the plumular leaf-trace persist for a time external to the cen- 
tral intercotyledonary protoxylem. The hypocotyl stele now consists of 
four protoxylem poles, two in the cotyledonary and two in the inter- 
cotyledonary planes in connexion with tangentially differentiated meta- 
xylem, and alternating with four phloem groups diagonally placed. An 
endodermis is present. In passing downwards the pith becomes smaller 
and tangential differentiation of the metaxylem is gradually replaced by 
centripetal, so that a typical tetrarch root structure is obtained above the 
collet. 
In C. tenuissima and C. stricta the anatomical features are similar 
to those above described. In the latter species an older seedling showed 
that secondary growth begins Very early in the region of the cotyledonary 
node, but is delayed at lower levels* 
C. inophloia , described by Chauveaud, 1 is tetrarch and resembles the 
above species. 
In these forms ‘transition ’ takes place in accordance with the cruciform 
tetrarch type previously referred to (see p. 577). 
PlPERALES. 
Mr. T. G, Hill 2 has described the seedling anatomy of members of this 
cohort, including several species of Piper and of Peperomia , all of which 
appear to conform to the diarch type. Peperomia peruviana , a geophytic 
form described by Mr. A. W. Hill, 3 and Piper excelsum referred to by 
M. Chauveaud 4 are also diarch. 
Salicales. 
Salicaceae. Seeds of several species of Salix and of Populus were 
obtained, but all except those which were sown immediately after ripening 
failed to germinate. 
Salix caprea , S. repens. These have very small epigeal seedlings. 
In each cotyledon petiole there is an extended strand which is resolved into 
a double bundle at the node. The two double bundles together constitute 
in the hypocotyl a diarch stele having central protoxylem in the cotyle- 
donary plane flanked by tangential metaxylem wings, and four phloem 
groups diagonally placed. Contraction of the stele with fusion of neigh- 
bouring phloems in the intercotyledonary plane produces a normal diarch 
root* 
Myricales. 
Myricaceae* Seedlings of only two species were obtained, and these 
were almost indistinguishable in external appearance. They are small, 
wiry, and slow growing. The cotyledons are epigeal. The first plumular 
1 loc. cit., p. 302. 2 loc. cit. 3 loc. eit. 4 loc. cit. 
