526 
CHRISTINE E. QUINLAN ON 
they approach the axis (c). On the flanks, the peripheral bundles become elongated 
tangentially (d), and the median foliar bundle approaches and gives off two lateral 
strands which diverge and fuse with the peripheral bundles. The latter separate 
and gradually contract till they reach their normal size. The median foliar finally 
becomes inserted in the central vascular ring ( e , f), and is eventually lost in the 
lower internode. The lateral foliar bundles, before joining the peripheral bundles, 
become inversely orientated. The same inversion takes place in the strands which 
leave the median foliar bundle to fuse with the peripheral bundles. The latter 
differ from those of Calycanthus in that they retain their sclerenchyma throughout 
the node. 
Summary. 
The most noteworthy anatomical peculiarities in the structure of the stem of the 
Calycanthacese are as follows : — 
1. The occurrence of two basipetal axillary buds. 
Two axillary buds occur in all the species of both genera. In Calycanthus, 
they expand into leafy shoots almost simultaneously, the outer being later in 
development. In Chimonanthus, the opening of the outer bud is delayed till the 
stem is in its fifth or sixth year. 
2. The occurrence of four vascular bundles in the pericycle. 
These bundles were found in all the species examined. Herail states that they 
are situated in the cortex of Calycanthus, and that in Chimonanthus they originate 
in the pericycle and move out later into the cortex. Lignier holds that they are 
both cortical, while Van Tieghem regards the bundles in Calycanthus as cortical, 
and those of Chimonanthus as pericylic. So far as Chimonanthus is concerned he 
is correct, but in Calycanthus an endodermis encircles the peripheral bundles along 
their outer margins, and hence they must be pericyclic in origin. In C. fertilis and 
C. jioridus the layer of pericylic sclerotic cells is continuous with the arc of scleren- 
chyma bordering the bundles exteriorly, again demonstrating the pericyclic origin of 
these bundles. As already stated, the bundles are inversely orientated. 
3. The presence of a heterogeneous pericycle. 
The pericycle consists of two kinds of fibres, viz. uniformly sclerotic fibres, and 
sclerotic cells wdth U-shaped thickenings. The latter are few in number in Caly- 
canthus, but are very numerous in Chimonanthus. In Calycanthus, the groups of 
uniformly sclerotic fibres never fuse to form a continuous pericycle. In that genus, 
the irregularly thickened cells occur either in isolated groups or joined to the groups 
of uniformly thickened fibres. In Chimonanthus, the gaps between the groups of 
uniformly thickened cells are filled with the second type of sclerotic cells in the 
second and third years. 
