10 OPHREiE. 'Jhap. I, 



consists of a mass of polygonal cells, full of brownish 

 matter, which cells soon resolve themselves into two 

 balls of extremely viscid semi-fluid matter, void of 

 structure. These viscid masses are slightly elongated, 

 almost flat on the top, and convex below. They lie 

 quite free within the rostellum (being surrounded by 

 fluid), except at the back, where each viscid ball 

 adheres to a small portion or disc of the exterior 

 membrane of the rostellum. The ends of the two 

 caudicles are strongly attached externally to these 

 two little discs of membrane. 



The membrane forming the whole exterior surface 

 of the rostellum is at first continuous ; but as soon as 

 the flower opens the slightest touch causes it to rupture 

 transversely in a sinuous line, in front of the anther- 

 cells and of the little crest or fold of membrane (see 

 fig. D) between them. This act of rupturing makes 

 no difierence in the shape of the rostellum, but con- 

 verts the front part into a lip, which can be depressed 

 easily. This lip is represented considerably depressed 

 in fig. D, and its edge is seen, fig. B, in the front view. 

 When the lip is thoroughly depressed, the two balls 

 of viscid matter are exposed. Owing to the elasticity 

 of the hinder part, the lip or pouch, after being 

 pressed down, springs up again and encloses the two 

 viscid balls. 



I will not affirm that the rupturing of the exterior 

 membrane of the rostellum never takes place sponta- 

 neously ; and no doubt the membrane is prepared for 

 rupture by having become very w^eak along defined 

 lines ; but several times I saw the act ensue from an 

 excessively slight touch — so slight that I conclude 

 that the action is not simply mechanical, but, for the 

 want of a better term, may be called vital. We shall 

 hereafter meet with other cases, in which the slightest 



