Chap. II. SOLANUM. 75 



tissue, with lines radiating from the centre. The 

 three groups of yessels, 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.* 



FuMAEiACEa;. — Fumaria offieinaUs. — 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 Masters informB surfaces. In accordance with this 



me that in almost all petioles statement, it may be observed 



which are cylindrical, such as that the enlarged and clasped 



those bearing peltate leaves, the petiole of the Solatium, with its 



woody vessels form a closed ring ; closed ring of woody vessels, has 



semilunar bands of vessels being become more cylindrical tlian it 



confined to petioles which are was in its original unclasped 



channelled along their upper condition. 



