246 PARASITISM OF CUSCUTA AND OROBANCHE 
wood evidently form the walls of the spaces which seem filled 
with gummy fluid matter. The wood, which would appear 
of one year’s growth and a little more, has two rather irre- 
gular lines of ductiform vessels, but is otherwise fibrous. 
In Populus the same occurs, the disc coming into contact 
with the external surface of the layer of wood, formed im- 
mediately before (? 
In this the remarkable circumstance of other axes being 
formed, takes place; and it is curious that in this instance, 
the sucker was divided inside the bark, one leg divaricate to 
the additional axis, the other following the usual course. In 
this there is an appearance of a central system of the sucker. 
.. Sketch of Populus tomentosa. Pl. 61. fig. 1 
a. Cutis. 
b. Cellular system of bark. 
Just forming wood. 
. Just formed wood. 
Last year's wood. 
A fuscous band— what is it ? 
Extra axis. . 
Leg of sucker. 
In this also the bark and wood form a continuous system, 
though the one separates pretty readily from the other. The 
newest formed wood separates with the bark with which 
it forms an integral part; immediately external to it as in 
Eleagnus, exists what appear to be reservoirs of gummy 
matter, the partitions which.are continuous with the medul- 
. lary rays separating, although always originally continuous 
throughout. These gummy looking places are no doubt the 
new wood, the septa are reduced in size by the growth of 
the wood, and become medullary rays. 
The distinct axis is most probably an error, the true struc- 
ture is this, the stem is prominently angular, and the angular 
nature affects every system except that of the pith. Thus 
the bark is angular, into these angles rounded bastions of 
wood enter, and into these woody portions enters the fuscous: 
system next the pitb, so that the specimen drawn was very 
deceptive, for, it having been torn across the end of the 
FTT & n 
