Anomalous Forms of Dicotyledonous Stems. 125 
Embryo-buds, first described by Dutrocbet*, and considered by 
him to be buds, which instead of becoming elongated are deve- 
loped on all sides, and, producing no leaves, are nourished by the 
sap of the bark. Prof. Treviranus remarks that this view is dif- 
ficult to reconcile with the generally received opinion that the 
formation of wood depends on the presence of leaves, and new 
investigations upon living specimens are very desirable ; it is ob- 
vious however that the production and development of secon- 
dary layers of wood occurs here, quite separate and distinct from 
the central primary ligneous body of the tree. [With regard to 
these remarks it may be observed, that it is only if we admit the 
notion that the new layers of wood actually grow down from the 
leaves, like roots, as is affirmed by Gaudichaud, that there is 
any difficulty in adopting DutrochePs views. If the leaves only 
elaborate the juices for the formation of new wood, the elaborated 
sap conveyed down in the bark and cambium-layer may go to 
form new layers around the nucleus it finds in the shape of an 
embryo-bud, just as readily as to increase the great central woody 
mass of the tree. — Rep.~\ 
The author next notices those stems in which, in addition to 
the central woody mass, from three to ten smaller ligneous 
masses occur surrounding the central one and increasing in size 
in proportion to it. Mirbel f first pointed out this structure in 
Calycanthus floriduSj and Gaudiehaud J in the Sapindacece. The 
course of the formation of the four secondary woody masses in 
Calycanthus is as follows : — In a young stem there are found 
four vascular bundles in the bark, distinct from the central wood, 
and from each other except at the nodes, at every one of which 
cross bundles uniting these together form a ring round the cen- 
tral body ; as the stem grows, new layers of woody substance are 
deposited on the inner faces of these bundles (which are of 
course carried outward with tlie bark to make room for the in- 
creasing thickness of the central mass of wood). These new 
layers are considerably thicker than the outer, previously formed ; 
they are also progressively wider, and thus form a somewhat cres- 
cent-shaped body (when seen in a transverse section) ; the horns 
of the crescent advancing outward gradually approach and meet, 
so as to include a portion of the bark, which then forms what 
resembles a kind of pith to it. This false pith of eaeh woody 
mass is thus of course excentrical, the woody layers which sur- 
round it being fewer and thinner on the outer side. 
In regard to the origin of this structure, Mirbel compared the 
four bundles to those lying in the angles of the square stem of 
• Nouv. Mem. du Mus. d’Hist. Nat. iv. 
t Ann. des Sc. Nat. xiv. J Archiv de Bot. ii. 
