12 



OPHREiE. 



Chap. I. 



it is scarcely possible that any object can bo push<'(l 

 into it without tlie rostelluni bein<i: touched. The ex- 

 terior membrane of tlie rostellum then ruptures in the 

 l)roi)er lines, and the lip or pouch is easily dejjressed. 

 When this is effected, one or both of the yiscid balls 

 will almost infallibly touch the intruding body. So 

 yiscid are these balls that whateyer they touch they 

 firmly stick to. Moreoyer the yiscid matter has 

 the peculiar chemical quality of setting, like a 

 cement, hard and dry in a few minutes' time. As the 

 anther-cells are open in front, when the insect with- 

 dra\\s its head, or when the pencil is ^\•ithdrawn, one 

 l)ollinium, or both, will be withdrawn, firmly cemented 

 to the object, projecting up like horns, as shown (fig. 2) 



Fi2. 2. 



^\w ^. 



A. J'tillen-mass of O. mascuht, when i ii. I'ollLU-inas.s of 0. mas:ula, after 

 first attached. [ the act of depression. 



by the uj>p(n- figure, A. The firmness of the attach- 

 ment of the cement is yery nt^cessary, for if th(! 

 polliuia were to fall sideways or backwards they could 

 never fertilise the flower. From the position in 

 which the two jiollinia lie in their cells, they diverge a 

 little when attachetl to any ol)ject. Now suppose that 

 tlie insect flies to another flower, or let us insert the 

 pencil (A, fig. '2), with the attached pollinium, into 



