AND HISTOLOGY OF PIPER BETLE. 361 
above description. Branches, monopodial or sympodial, always begin with 
an abbreviated internode. The node succeeding any abbreviated internode 
always bears a mere sheath. Flower-production, which may, however, be 
aborted, is always correlated with sympodial structure. The sympodial unit 
has always one or more elongated internodes in a line with the main axis, 
as also one sheath and as many leaves as there are long internodes. 
Branch-casting.—This requires a brief notice. Under natural conditions, 
before the time arrives for branch-casting the whole vine is lowered by the 
cultivators and buried. Тһе phenomenon of branch-casting does not 
therefore normally occur under field conditions ; it can, however, be easily 
contrived by placing a sufficient length of the vine in a moist chamber. 
A branch borne by the leader comes off from the first node above the short 
internode, leaving that internode invariably attached to the mother axis 
(Pl. 17. fig. 13 at the apex). Higher up the branch, too, wherever there 
are two approximated nodes, the severance takes place at the upper node. 
Buds. 
Situation —The bud is invariably axillary, whether on the leader or on 
the branches. All leaves and sheaths are provided with a bud. On the 
other hand, accessory buds are not formed. In accordance with these 
facts, we get, in the course of a branch at the sympodial joint where 
two nodes are approximated, a bud at the upper node alone. As this one 
bears the caducous sheath, the bud is always exposed to view. No bud is to 
be seen or expected at the lower node of the two approximated ones, 7. e. in 
the axil of the ordinary leaf, for the bud whieh was there has already 
developed to form the sympodial unit lving over the lower node ; in other 
words, it is the starting-point of a sympodium. The buds in the axil of all 
sheath-bearing nodes are situated so as to point either directly or obliquely 
upwards. 
Development.—The buds in different parts of the plant have definite 
characteristics in this respect. The terminal bud of the leader will be 
considered first. Its growth is continuous, so that below the bud we get 
a regular gradation in size both of the internodes and leaves (PI. 17. fig. 1). 
The terminal bud of a lateral branch, on the other hand, develops by stages. 
It halts at every sheath, which, as we have seen, almost regularly alternates 
with a leaf, and does not unfold until the last regular leaf attains, or nears 
the attainment of, its full size. 
As regards the axillary buds on the leader, such of them as are to develop 
into lateral branches start their development without any period of rest 
preceding it; hence we find a succession of lateral shoots on the leader 
below its apex developed in a graded manner, the smallest being uppermost 
(Pl. 17. fig. 1). 
Of the axillary buds on the lateral branches, those in the axil of a leaf 
