FLOWER OF PINGUICULA VULGARIS, ETC. 641 



extremity of the floral axis. The two anterior are developed first (Plate XXVIII. 

 fig. 3). Of the lateral sepals and the posterior one, I have not been able satis- 

 factorily to determine the relative time of appearance ; but there can be little 

 doubt that the lateral precede the posterior. The sepals soon become connate 

 with each other ; but unequally so, the two anterior with each other, and the 

 posterior with the lateral, respectively forming an anterior lip with two lobes, 

 and a posterior with three. These lips are almost free from each other, the 

 antero-lateral connation being very slight. When the sepals are sufficiently 

 developed to cover in the young flower-bud, they are found, in the great majority 

 of cases, so arranged, that the posterior sepal is overlapped by the lateral ones, 

 which are in turn overlapped by the anterior (Plate XXIX. fig. 15). The anterior 

 sepals, as a rule, have not their surfaces in contact.* 



Corolla. 

 The examination of the earliest appearance of the corolla has been the most 

 unsatisfactory part of my research. Its parts very soon become connate, if, 

 indeed, they are not " congenital ly" so. I am inclined to think that, as in the 

 calyx, its anterior portion is developed first ; the anterior petal appearing to me 

 to be a more salient projection than the others in the early condition. In Plate 

 XXVIII. fig. 4, I have represented a young flower, where the corolla is seen as a 

 rim-like, faintly angular edging to the receptacle, just within or above the calyx, 

 its angles- alternating with the sepals. Here the stamens have not yet made their 

 appearance, unless the very slight furrow in the middle line anteriorly be held 

 as indicating, indirectly, the presence of the anterior stamens, one on either side 

 of it. At this stage the centre of the receptacle is seen to exhibit a slight con- 

 cavity, chiefly in the antero-posterior direction, a concavity which becomes still 

 more marked in the subsequent stages represented in Plate XXVIII. figs. 5 and 6, 

 and which I shall have further occasion to refer to in connection with the de- 

 velopment of the pistil. The growth of the corolla appears to continue uninter- 

 ruptedly until its full development, not exhibiting the pause which occurs so 

 frequently in its course in other plants. As the calyx does not at all keep pace 

 with the corolla, the latter soon forces its way from between the sepals, which 

 at an early period are folded over it ; and, in consequence of this, it is only 

 in comparatively young flower-buds that the aestivation of the sepals can be 

 observed. A little before the sepals are thus pushed aside, the spur of the corolla 

 begins to appear, as a small dilatation from within of the tube of the corolla at 

 its base, in the middle line anteriorly, indicated externally by a rounded knob- 



* Exceptions are sometimes met with. I have seen the posterior sepal overlapping only one of 

 the lateral ; or one, or both of the lateral sepals wholly external. A hasty observation of such an 

 exception as the last, probably led Payer (Lecons, p. 14) to describe the aestivation of the calyx as 

 quincuncial, which I can hardly believe it ever is. 



