Chap. IV. EPIPACTIS PALUSTRIS. 95 



stigma is bilobed and projects in front of the column 

 (see s in the side and front views, C, D, fig. 15). On 

 its square summit a single, nearly globular rostellum 

 is seated. The anterior face of the rostellum (r, 0, D) 

 projects a little beyond the surface of the upper part of 

 the stigma, and this is of importance. In the early bud 

 the rostellum consists of a friable mass of cells, with the 

 exterior surface rough : these superficial cells undergo 

 a great cliange during development, and become con- 

 verted into a soft, smooth, highly elastic membrane or 

 tissue, so excessively tender that it can be penetrated 

 by a human hair ; when thus penetrated, or when 

 slightly rubbed, the surface becomes milky and in some 

 degree viscid, so that the pollen-grains adhere to it. 

 In some cases, though I observed this more plainly in 

 EpiiKidis latifolia, the surface of the rostellum appa- 

 rently becomes milky and viscid without having been 

 touched. This exterior soft elastic membrane forms 

 a cap to the rostellum, and is internally lined with a 

 layer of much more adhesive matter, which, when ex- 

 posed to the air, dries in from five to ten minutes. 

 By a slight upward and backward push with any object, 

 the whole cap, with its viscid lining, is removed with 

 the greatest ease ; a minute square stump, the basis 

 of the rostellum, being alone left on the summit of the 

 stigma. 



In the bud-state the anther stands quite free behind 

 the rostellum and stigma ; it opens longitudinally 

 whilst the flower is still unexpanded, and exposes the 

 two oval pollen-masses, which now lie loose in their 

 cells. The pollen consists of spherical granules, co- 

 hering in fours, but not affecting each other's shapes : 

 and these compound grains are tied together by fine 

 elastic threads. The threads are collected into bundles 

 extending longitudinallv along tlie middle line of the- 



