412 Prof. C. Morren on the Morphology of the Ascidia. 



of the blade of the leaf. The leaf coheres by its margins and 

 above, absolutely as in the formation of carpels, which made 

 me say that the ascidium is a tendency to the floral form. 

 Since this period new facts have confirmed this theory. Du- 

 ring my stay at Newcastle in Northumberland, at the Meet- 

 ing of the British Association, I had an opportunity of study- 

 ing the different preparations of monstrosities which the Rev. 

 W. Hincks of York, known by his f Monograph of the CEno- 

 theraf had brought there. Amongst these specimens were 

 two of the most remarkable accidental ascidia, and which per- 

 mit us to classify these extraordinary deviations. One was on 

 a specimen of Tulipa gesneriana. The leaf which, as is well 

 known, sheaths the peduncle in this plant, had cohered at its 

 free margins along its whole length, so that the outer surface of 

 the pitcher thus formed was always the under surface of the 

 leaf. But it resulted also from the complete cohesion of the 

 margins of this organ that no aperture allowed of any communi- 

 cation between the outward air and that inclosed in its cavity. 

 Nevertheless a flower and its peduncle were inclosed in this ca- 

 vity, and the perianth was not less finely coloured through this 

 envelope than are the petals of Papaver rhoeas under the 

 thick tunics of their caducous calyx. As the flower deve- 

 loped, it was necessary that the peduncle should grow larger, 

 which it did to a greater degree than the ascidimorphous leaf, 

 which remained small ; but then it was also necessary that the 

 peduncle should twist itself or that the ascidium should burst. 

 The peduncle prevailed, and the ascidium opened ; but not, as 

 would have been supposed, by a longitudinal rupture occasion- 

 ed by a dislocation of the cohering margins, but by another 

 very curious way of dehiscence. The ascidium formed an elon- 

 gated bag; tumid in the middle, tapering at its two extremi- 

 ties, above and below : now this bag was split across with 

 a horizontal rupture, just as in the ascidium the lid is de- 

 tached from the pitcher, or rather as in mosses the calyptra 

 falls off from the urn. The flower indeed carried this cap with 

 it and could not rid itself of it, so that the perianth remained 

 curled up beneath and within. At sight of this tulip, having 

 at its base a conical foliaceous hollow body, from the centre 

 of which arose a long peduncle, terminating in its turn in 



