1885.] FERTILIZATION OF BRITISH ORCHIDS. 509 



in front when the insect withdraws its head, or wlien the pencil is 

 withdrawn (Fig. 4), one pollinium or both will be withdrawn, firmly 

 cemented to the object, projecting up like horns, as shown in Fig. 4. 

 The firmness of the attachment of the cement is very necessary, for 

 if the pollinia were to fall sideways or backwards, they could never 

 fertilize the flower. From the position in which the two pollinia 

 lie in their cells, they diverge a little when attached to any object. 

 Now, suppose that the insect flies to another flower, or let us insert 

 the pencil (Fig. 4) with the attached pollinium into the same or 

 into another nectary ; by looking at the diagram (Fig. 3) it will be 

 evident that the firmly-attached pollinium will be simply pushed 

 against or into its old position, namely, into the anther cell. How 

 then can the flower be fertilized ? This is effected by a beautiful 

 contrivance ; though the viscid surface remains imnioveably affixed, 

 the apparently insignificant and ininute disc of membrane to which 

 the caudicle adheres, is endowed with a remarkable , power of con- 

 traction which causes the pollinium to sweep through 'an angle of 

 about 90 degrees, always in one direction, viz. towards the apex of the 

 proboscis or pencil, in the course of 30 seconds on an average. The 

 position of the pollinium after the movement is shown in Fig. 5, 

 After this movement, completed in an interval of time which would 

 allow an insect to fly to another plant, it will be seen, by referring 

 to the diagram (Fig. 3), that if the pencil be inserted into the 

 nectary, the thick end of the pollinium now exactly strikes the 

 stigmatic surface." The stigma itself, although very viscid, is] not 

 sufficiently so to pull the whole pollinium from the insect's head, 

 and yet sufficiently viscid to break the elastic thread and retain a 

 sufficient quantity of the pollen to fertilize the flower. One 

 pollinium, therefore, suffices to fertilize several flowers. The pouch 

 springs back after being depressed so as to keep the other pollinium 

 (if only one has been removed) moist. 



Little difference exists between the action of the organs of 

 0. mascula, and those of 0. fusca, 0. morio, 0. maculata, 0. latifoJia, 

 Ophrys aranifcra, 0. muscifcra, and Herminiuvi monorchis. In 

 Orchis jyyramidalis, however, there is but one viscid disc which is 

 saddle-shaped instead of, as in 0. mascula, where there are two and 

 rounded, and the pollinia after becoming attached to an object not 

 only undergo the regular act of depression, but are previously, by 

 the curling or clasping movement of the viscid disc, caused to 

 diverge to the proper angle so as to strike the two lateral stigmas. 

 0. ustulata and 0. hircina resemble the latter species in the pollinia 

 arising from a single disc, but only in 0. ustulata does a slight 

 divergence of the pollinia take place. In 0. or Ncotinca intacta, 

 the pollen from being extremely incoherent falls spontaneously on 



