SECT. V. THE FRUIT. 153 



the Pink. All pericarps do not open in the same 

 manner ; but all individuals of the same species 

 open in the same manner ; and the pericarp is said 

 to be one-valved, two-valved, three- valved, or many- 

 valved, according to the number of valves into 

 which it opens. 



The form and contexture of the valves is as much 

 diversified as the form and contexture of the fruit. 

 But the external surface is generally convex, and 

 marked with a longitudinal furrow ; and the in- 

 ternal surface generally concave. The margin is 

 simple or inflected, forming often a prominent 

 seam which connects the valves. But sometimes 

 the valves are connected by means of an additional 

 substance inserted between them. In the Lily it 

 is a fine membrane resembling a net, in the Tulip 

 it is rough and bristly. 



The aperture by which the valves open sponta- 

 neously is generally longitudinal, extending in 

 many cases from the top to the bottom of the 

 pericarp, as in Galanthus ; but in other cases ex- 

 tending only half way down, as in Chrysosplenium, 

 and forming semi-valves ; and in others extending 

 for a space so very short that the pericarp is only 

 said to be toothed, as in Primula. But sometimes 

 also the aperture is transverse or horizontal, as in 

 Centunculus, Hcdysarum, and Anagallis. In most 

 plants, as in Pyrola, the valves open externally ; 

 but in Colchicum they open internally ; and in 

 Triglochin the opening is from the base upwards. 



