312 Prof. Ch. Morren on the Morphology of the Ascidia. 



purpurea, rubra, variolaris and Jlava, which I have particu- 

 larly examined, there is everywhere a prominent crest which 

 imitates a phyllodium perfectly ; it is very decided upon Sar- 

 racenia purpurea and variolaris ; then come the rubra and the 

 flava, where it is least developed. Upon the variolaris, at 

 the aperture of the urn^ on the side opposite to the opercular 

 lamella, we see that the crest is formed of two cohering 

 blades, which diverge or separate to form the urn. Moreover 

 there is upon the urn, on the side opposite to the crest, a 

 principal nerve which evidently represents the medial nerve 

 of the blade of the leaf; the crest is merely the junction of the 

 margins of the blade, and the urn is the cavity which results 

 from this cohesion. It is here a simple leaf of which the two 

 lateral portions of the blade are conjoint. This seems to me 

 to be so true that the accidental ascidium of Polygonatum of- 

 fered the greatest affinities with the permanent ascidium of 

 Sarracenia rubra, only that the crest and the struma were 

 not present, but the opercular lamella presented equally the 

 same form and the same arrangement. This opercular la- 

 mella is not articulated as in Nepenthes, and does not differ 

 in the system of neuration from the rest of the apparatus ; it 

 represents then simply the extremity of the ascidimorphous 

 leaf, the margins of which extremity do not cohere. Upon 

 the accidental ascidium of Vinca rosea the operculiform la- 

 mella was much larger in proportion to the size of the hollow 

 cavity. 



When we examine the origin of the ascidium oi Sarracenia 

 purpurea we see that it is the crest which first forms and 

 grows quickly ; towards its principal nerve there is a cylin- 

 drical hollow tube which is subsequently developed into a 

 pitcher. This tube is at first closed by the circinate disposi- 

 tion of its extremity, and in this species two small lateral la- 

 mellae separate to form the opening of the pitcher. These two 

 lamelloe become in the purpurea the two lips which serve as 

 an operculum to shut the pitcher like two lateral valves. Their 

 junction, instead of being elongated into an opercular blade as 

 in the other species mentioned, is on the contrary grooved. 

 There is here an organic compensation ; the substance of the 



