FLOWER OF PINGUICTTLA VULGARIS, ETC. 643 



being scarcely distinguishable from the normal stamens. In Plate XXX. fig. 31, 

 I have represented the essential organs of a flower where a moderate degree of 

 this condition is to be seen, accompanied by an interesting reversion to regularity 

 in the stigma, to which I shall afterwards refer. 



Pistil. 

 The pistil appears very quickly after the development of the androeciurn ; it 

 being a matter of some difficulty to find a flower with the staminodes visible 

 that does not, at the same time, exhibit some vestige of the pistil. It makes its 

 first appearance as a semilunar elevation placed anteriorly just within, or (from 

 the downward slope of the receptacle) below the two fertile stamens, with which 

 it alternates. The extremities of this semilunar elevation gradually extend 

 themselves around the organic centre of the receptacle, till they meet in the 

 middle line posteriorly. The ovarian wall, thus completed, grows up as a short 

 tube, which very soon exhibits a tendency to bilabiation, the result of pre- 

 ponderating growth, anteriorly and posteriorly (Plate XXVIII. fig. 9). The orifice 

 of the short tube constituting the young ovarian wall, at first nearly circular, 

 very soon becomes narrowed in the antero-posterior direction. This narrowing, 

 apparently, is mainly caused by the inclination of the anterior and posterior 

 walls towards each other, in consequence of the antero-posterior concavity of 

 the receptacle, to which I have above alluded.* The antero-posterior inclination 

 towards each other of the ovarian walls, is well seen in the sections represented 

 in Plate XXIX. figs. 12 and 13. The anterior and posterior walls thus inclined 

 towards each other, at last come in contact, whereby the cavity of the ovary is 

 closed in above. From this point of contact the lips of the ovarian margin, in 

 their further development, curve away from each other ; the one posteriorly as 

 a narrow strap-like body ; the other anteriorly as a broadly expanded lamina, 

 which rests upon and ultimately wholly conceals the anthers of the two fertile 

 stamens (Plate XXIX. fig. 11). These lips become covered on their upper 

 surface by papillae, and together constitute an unequally bilabiate stigma. The 

 part where the ovarian walls are in contact becomes somewhat elongated (ap- 

 parently to a variable extent), and constitutes the short style. The basal portion 

 of the pistil becomes dilated, forming the ovary proper. It is to be noted that 

 the ovary is to a certain extent inferior posteriorly- — that is to say, its cavity 

 posteriorly extends distinctly below the level of the insertion of the calyx and 

 corolla. 



Placenta and Ovules. 



In the earlier stages of the development of the flower, and up to the time when 



* The slight bilabiation of the ovarian orifice seen in Plate XXVIII. fig. 9, though real, is 

 <loubtless in appearance considerably exaggerated by this antero-posterior narrowing. 



VOL. XXV. PART II. 8 E 



