SEEDLING STRUCTURE IN THE LEGUMINOZA. 117 
The following are in brief the main conclusions attained from this study :— 
(i.) The stable tetrarch type of symmetry is found typically in seedlings of 
large size. 
(i.) The production of large seeds and seedlings is correlated with the 
tree-habit. 
(11.) The arboreal habit is in all probability primitive in the Leguminose, 
as in Angiosperms generally, the herbaceous habit derived. 
(iv.) The stable type of tetrarchy is therefore probably fundamental and 
primitive for the whole family. 
(v.) Reduction in the size of the seedling has given rise to an unstable type 
of tetrarchy, in which the intercotyledonary xylems, though cotyledonary in 
nature, stand in an intimate supplementary relation to the early plumular 
traces. 
(vi.) Triarchy and diarchy are closely associated with this unstable form of 
tetrarchy. The whole group of types of symmetry is in a highly variable 
condition, all three forms co-existing within single tribes, genera, species, and 
even individuals. 
(vii) Diarchy is the final term in this reduction-series ; and when attained 
it is often extremely stable. 
(viii.) The whole series given above applies mainly to epigeal types. In 
cases of hypogeal germination, in which the plumule develops fast, the 
epicotyledonary traces may be directly represented by primary xylem in the 
root. 
(ix.) In particular the hypogeal Vicies exhibit a very constant triarch 
structure, in which two xylems are cotyledonary, the third plumular. This 
type has no connection with the epigeal form of triarchy. 
(x.) Other types of structure found in the family are also derivable from 
the stable form of tetrarchy. 
(xi.) The anatomical transitions from root- to stem-structure are classified 
into three main and two subsidiary grades according to the level at which 
they take place. Low transitions are characteristic of massive, high tran- 
sitions of slender, hypocotyls; while intermediate transitions are found in 
hypocotyls of intermediate diameter. 
(xii. The diameter of the axis is the most important factor in determining 
the level of transition: length of hypocotyl has a subordinate, and largely 
psychological, effect. 
(xiii.) Since both the type of symmetry and the level of transition are so 
closely related to the size of the seedling, it appears that these anatomical 
characters are not likely to be of more value in solving phylogenetic problems 
than the size-characters themselves. 
(xiv.) Within narrowly restricted groups, however, it seems that a type of 
symmetry, or a certain arrangement of bundles or vascular elements, or even 
