:)QG Prof. Ch. Morren on the Morphology of the Ascidia. 



a case of monstrosity upon two plants, the leaves of which 

 generally offer no similarity at all; and the examination of these 

 two vegetable monstrosities, which I would rather term simple 

 anomalies, afford me an opportunity of putting forth some new 

 ideas on the formation of the ascidia. In fact, the question 

 is to know whether the ascidia are modifications of the pe- 

 tiole or whether they are derived from the blade of the leaf; 

 whether they are petioles which arc become hollow, or whe- 

 ther they are the blades of leaves cohering at their margins 

 in the form of pitchers. Mr. Lindley thinks that they are 

 hollow petioles, although he himself admits, whilst declaring 

 this principle, that the ascidia are fistular bodies occupying 

 the place and performing the functions of leaves. 



The pitcher is the true petiole according to him, and the 

 operculum which covers the hollow part is the blade of the 

 leaf in an extraordinary state of transformation. This illus- 

 trious English botanist arrives at this idea by the analogy 

 which he finds between the structure of the leaves of Dioncea 

 muscipnla and those of Nepenthes and Sarracenia, having found 

 another between the three families, the Sarracenia, the Dro- 

 seracea, and the Nepenthece, to which these plants belong*. 

 In the Dioncea muscipnla he says, the leaf consists of a broad- 

 winged petiole, articulated with a collapsing blade, the mar- 

 gins of which are pectinate and inflexed. Let us suppose, he 

 continues, the broad-winged petiole to collapse also, and that 

 its margins, when they meet, as they would in consequence of 

 a collapsion, cohere ; a fistular body w T ould then be formed 

 just like the pitcher of the Sarracenia ; and in this case there 

 wiH be no difficulty in identifying the acknowledged blade of 

 the Dioncea with the operculum of Sarracenia. From Sarra- 

 cenia the transition to Nepenthes would perhaps not be con- 

 sidered improbable f. 



We see then that Mr. Lindley views the ascidia of Ne- 

 penthes and of Sarracenia as a deviation of form of a winged 

 petiole, the upper surface of which is become the outer surface 

 of the pitcher ; the under surface of the petiolar blade would 



* Natural System of Botany, p. 152 — 155. 

 t Introduction to Botany, p. 118 — 119. 



