FLOWER OF PINGUICULA VULGARIS, ETC. 649 



Remarks on the Embryos of Pinguecula vulgaris, P. grandiflora, P. lusitanica, 

 P. caudata,* and Utricularia minor. 



The remarkable diversity in the structure of the embryo in the Lentibu- 

 lariacese is, perhaps, one of the most extraordinary circumstances connected 

 with the order. A. de St Hilaiee pointed to the occurrence of a dicotyledonous 

 embryo in P. lusitanica, a monocotyledonous one in P. vulgaris, and an acotyled- 

 onous one in Utricularia vulgaris, as an instance of how the most important 

 characters may vary, even within the limits of a single order.f 



Treviranus, in 1838,]; was the first to show that the embryo of P. vulgaris 

 has only one cotyledon. In 1848, he published his researches on its germination, 

 which were called forth by a statement of Klotzsch's, that this embryo germin- 

 ates with two cotyledons, of which one is much smaller than the other. Here, 

 he showed that Klotzsch's smaller cotyledon does not appear until germination 

 is considerably advanced, thus proving that it does not legitimately fall under 

 the definition of a cotyledon at all.§ 



P. vulgaris, L. (Plate XXX. figs. 33-40). 



The embryo of Pinguecula vulgaris, taken as a whole, is of a cylindrical form, 

 with rounded extremities, and measures about ^d of an inch in length. The 

 single cotyledon constitutes about one-half of the entire length of the embryo, 

 and is folded upon itself in a conduplicate manner, its margins being approximate 

 and parallel to each other, except towards the base, where they diverge rather 

 suddenly, leaving a considerable interval, where the termination of the embryonic 

 axis (rudimentary plumule) is to be seen (fig. 33). The apex of the cotyledon is 

 almost constantly entire, or, at least, not sufficiently emarginate to appear dis- 

 tinctly so in a back view, such as is represented in fig. 34. In two, or at most 

 three instances, however, out of the large number of embryos that I have 

 examined, the tip of the cotyledon was somewhat bifid, as is seen in the back view 

 in fig. 35. When sections made in the mesial plane (fig. 38) and at right angles 

 to it (fig. 37) are compared, the rudimentary plumule is seen to be compressed 

 laterally, having a strong convex curvature from side to side, while there 

 is only the slightest possible convexity from before backwards. That there 



* The observations on the embryo of this species were made after the paper had been sub- 

 mitted to the Society. 



f Morphologie, pp. 755-6. 



J In a communication to a meeting of naturalists, at Freyburg in Br., of which I have 

 seen no report, but which is referred to by Tkeviranus in his subsequent paper in the Bot. 

 Zeitung, 1848. 



§ Botanische Zeitung, 1848, p. 444. 



