888 Mr. Griffith on the Structure of the Ascidia and Stomata 



inclining to glaucous. Internally they are of a rich dark purple, studded 

 with innumerable and very minute white spots. 



The colour of the inflected portion internally is much lighter than that of 

 the corresponding surface of the leaf: its outer surface is of a light purplish 

 brown (Tab. XVII. fig. 1). They appear at no period to contain fluids, but 

 invariably contain one or more branched roots, which, taking their origin 

 from various parts of the petiole, pass down through the opening. These 

 roots are always more succulent and of a lighter colour than those formed in 

 any other part. Their structure is precisely that of the limb of the leaves ; 

 the only difference being in form and in the colour of the inner surface, which 

 corresponds to the concave of the leaves*. This structure presents nothing 

 peculiar, with the exception of the Stomata, to which I shall hereafter recur. 

 The proofs I have to give of their being modified laminae are : — 



1. Their similarity in texture and internal structure, and that of the stomata 

 with those of the limb of the leaves. 



2. There is a constant and appreciable though slight tendency in the limb 

 of the leaves to assume an involute form, their margins and apex being always, 

 and especially in old leaves, more or less incurved. 



3. The occurrence of an imperfectly transformed pitcher (Tab. XVII. fig. 2), 

 in which the body of the pitcher is clearly referable to the limb of the leaf. 

 The petiole has retained its usual form. This specimen resembled closely the 

 bottom of a perfect pitcher, being however much less compressed : it was 

 completely open at the top, no constriction having taken place. The margins 

 and apex were slightly incurved : there was a slight tendency towards colo- 

 ration, but only towards the fundus. 



4. In this family at least, it is more natural to refer the Ascidia to the limb, 

 from the general construction of their petioles. 



If we can extend the analogy drawn from the structure of the Ascidia of 

 this plant to the other cases of their formation, in Nepenthes, Cephalotus and 

 Sarracenia, in which the development is much more perfect, we shall have a 



* The leaves are smooth and somewhat concave on one surface, convex and rugose on the other ; 

 but the whole growth is so straggling, that it is difficult to sfiy which is the upper and which the under 

 surface. I think the inner surface of the pitcher corresponds to the upper of the leaves, that being the 

 smooth concave surface. 



