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SEEDLING STRUCTURE IN THE LEGUMINOSAZE. 
SUMMARIES OF THE DIFFERENT GROUPS. 
MIMOSOIDEZE. 
The number of species of this sub-order which have been examined up to 
the present is comparatively small. Examples from four tribes have been 
investigated, but the sub-order may well be treated as a whole in the present 
condition of our knowledge. 
The prevailing habit is arboreal, Schrankia uncinata being the only 
herbaceous perennial species yet examined. 
In most cases the embryo is straight, and is often surrounded with 
endosperm. Germination is usually epigeal, but Pithecolobium Unguis-cati 
has large fleshy subterranean cotyledons. The seedlings vary much in size 
and in the thickness of the cotyledons, In the Acaciee and Eu-Mimose:e 
the cotyledons are rather thin and the seedlings are small ; the hypocotyl is 
distended at the base into a prominent ring or collar composed entirely of 
cortical parenchyma. In the Ingeæ and Adenantherez larger seedlings 
occur with fleshy cotyledons and often no hypocotyl-collar. 
The tetrarch type of symmetry occurs throughout the sub-order ; but in 
Pithecolobium Saman the root is octarch changing to tetrarch below the collet. 
The level of transition varies from * intermediate? in the smallest seedling 
studied to “low” in the two largest. The other species exhibit transitions 
in which a tangential position of xylem is attained at the collet region, this 
persisting through a great part of the hypocotyl and resulting in collateral 
bundles with exarch xylem at the cotyledonary node: this type being 
described as * intermediate-low.” 
The Асасїе are characterised by the division of the original “ ectophloic 
siphonostele?' at the protoxylem, four tangentially differentiated bands of 
primary xylem being the result. 
The Eu-Mimose: have the two inner xylems of each cotyledon trace some- 
what smaller than the two outer: four bundles are only just recognisable in 
some cases, and the phloem is in two groups supplying each cotyledon. 
The Inge: and Adenantherez agree in the occurrence of large seedlings 
with a wide pith in the root surrounded by wedge-shaped distinct primary 
xylems: the transition being low. Albizzia moluccana (Inge), however, has 
" transition shows features in 
a smaller seedling, whose “ intermediate-low 
common with Acacieæ and Eu-Mimosez. 
The primary xylem of the root is usually cotyledonary : but in Pithe- 
colobium Unguis-cati, an hypogeal species, the plumular traces connect 
directly with the proto- and metaxylem of the lateral root-poles. 
A histological feature of the hypocotyl found also in many Ceesalpinioidex, 
is the presence of a zone of small-celled and sometimes thick-walled tissue in 
the outer part of the cortex. Fibres are very generally present in the 
hypocotyl between the phloem and the endodermis. 
