Cuap. II. SOLANUM, vi) 
tissue, with lines radiating from the centre. The 
three groups of vessels, which, though near together, 
were before distinct, are now completely blended. 
The upper part of this ring of woody vessels, formed 
by the prolongation of the horns of the original semi- 
lunar band, is narrower than the lower part, and 
slightly less compact. This petiole after clasping the 
stick had actually become thicker than the stem 
from which it arose; and this was chiefly due to the 
increased thickness of the ring of wood. This ring 
presented, both in a transverse and longitudinal 
section, a closely similar structure to that of the 
stem. It is a singular morphological fact that 
the petiole should thus acquire a structure almost 
identically the same with that of the axis; and it 
is a still more singular physiological fact that so great 
a change should have been induced by the mere act 
of clasping a support.* 
Foumariace2.—Fumaria officinalis—It could not 
have been anticipated that so lowly a plant as this 
Fumaria should have been a climber. It climbs by 
the aid of the main and lateral petioles of its com- 
pound leaves; and even the much-flattened terminal 
* Dr. Maxwell Mastersinforms surfaces. In accordance with this 
me that in almost all petioles 
which are cylindrical, such as 
those bearing peltate leaves, the 
woody vessels form a closed ring ; 
semilunar bands of vessels being 
confined to petioles which are 
channelled - along their upper 
statemeut, it may be observed 
that the enlarged and clasped 
petiole of the Solanum, with its 
closed ring of woody vessels, has 
become move cylindrical than it 
was in its original unclasped 
condition, 
