414 Prof. C. Morren on the Morphology of the Ascidia, 



structure which is shown, and thus the ascidium is always a 

 dependence, a result of the retrograde metamorphosis. It ap- 

 pears to me that these are facts irrevocably added to the study 

 and science of vegetable monstrosities. 



But what rendered the ascidium of the Polygonatum of Mr. 

 Hincks to me extremely curious, was to see it composed of 

 two leaves instead of one. The two terminal auricles, which 

 were in extent about a quarter of the total length of the asci- 

 dium, are in fact the tops of the two leaves, which by their 

 cohesion had formed these ascidia ; each of these auricles cor- 

 responded with a principal nerve. The leaves of the Polygo- 

 natum, instead of originating at different heights, are here al- 

 most perfectly opposite ; they have then cohered two by two 

 at their margins, which w^ere primitively and normally free, so 

 as to make a common cavity of their upper surfaces. This 

 same fact is repeated in three successive pairs. 



This binary origin of the ascidium is, I believe, unique in 

 the known cases of monstrosity, and in spite of its apparent 

 deviation it comes within the general law in the most com- 

 plete manner : the lower surface of the leaf remains the out- 

 side ; it is the blade which has formed the pitcher ; and the 

 latter is only owing to a cohesion of the margins. These three 

 circumstances, which are in perfect accordance with what I 

 have before established, are worthy of remark. 



Hence it is evident that the following classification may be 

 estabhshed amongst the anomalous ascidia hitherto observed : 



The ascidia are either formed of one leaf only or of several ; 



The monophyllous are the first ; 



The polyphyllous the second. 



A. The monophyllous ascidia, are, 1. either sarraceni/orm 

 when they are formed by a leaf cohering at its margins to form 

 a pitcher, so that the blade exceeds the aperture of the urn at 

 its summit as the opercular blade does in Sarracenia. The 

 ascidia of Vinca rosea and Polygonatum mentioned in my 

 former paper belong to this class of ascidia. 



2. Or calyptrimorphous, when they are formed by a leaf 

 cohering at its margins, but the upper part of which is de- 

 tached horizontally, as in the Tulipa gesneriana of Mr. Hincks. 

 This form, instead of reminding us of the Sa7'racenia, ap- 



