SEEDLING STRUCTURE IN THE LEGUMINOS.E. 29 
Two centimetres below the collet the root is of the usual diarch type ; 
there are two large wedges of primary xylem, the protoxylem being 2-seriate 
and the metaxylem broadening inwards to 6-7-seriate ; a narrow pith 
separates the two masses of xylem. There are two long lateral bands of 
phloem, with one or two layers of fibres separating them from the single 
parenchymatous pericycle layer. 
The transition takes place entirely below the external collet. The usual 
stages are passed through rapidly while the root is dilating to the diameter of 
the hypocotyl. A Y-shaped configuration is at first assumed ; then the proto- 
xylem becomes detached from the pair of massive metaxylems, which are 
gradually opening out into the tangential position and soon afterwards them-. 
selves separate. Meanwhile the phloems with the fibres have divided, and. 
each of the four groups thus formed has come to lie radially outside one of 
the metaxylems. А redistribution of the four collateral bundles then takes 
place, and in the hypocotyl they are equidistant from one another ; so that 
the cotyledonary plane can only be found by looking for the small half- 
obliterated root protoxylems which still lie in it. 
This structure, with the addition of a few plumular bundles, continues. 
throughout the hypocotyl. The cotyledon trace consists of the two large 
collateral bundles and the minute intervening protoxylem, which are all in 
direct connection with a single root-pole. The median protoxylem is 
exceptional in sometimes having a small group of phloem radially outside. 
it, thus composing a small collateral bundle. This feature has also been. 
found elsewhere (e. g., Helianthus annuus), but appears to be of very rare. 
occurrence. 
Lupinus HIRSUTUS, Linn. 
Stout annual herb with stems 30-40 em. high. Hypocotyl 2:0 mm. in 
diameter at the base, where it is circular in section, 5'0 x 2*0 just below the 
cotyledons, where it is elliptical ; narrows rather abruptly to a long stout 
primary root.  Cotyledons broadly oblong, bent to one side, owing to 
accumbeney of embryo, remaining fleshy and not becoming very leaf-like, 
though turning green in light. 
The phenomena of transition closely resemble those in Г. mutabilis. As in 
that species, the root is diarch, the transition is completed below the collet, 
and the whole of the hypocotyl is stem-like. Phloem, however, was not 
observed accompanying the median polar protoxylem in the cotyledon 
trace. 
Lupinus LUTEUS has been examined by Kattein (1897, p. 94), who states 
that cotyledons lie transversely to the plane of the root protoxylems ; that 
the adjoining lateral pairs of collateral bundles enter the cotyledons ; and that 
the polar protoxylems pass up into the epieotyl. These statements require 
