508 FERTILIZATION OF BRITISH ORCHIDS. [Dec. 



capsules are produced. As the method of fertilization by the 

 removal of the pollinia by insects is much alike in all our native 

 orchids, and also that to describe even one species of each genus 

 would occupy more space than is at our disposal, we therefore pur- 

 pose describing in as concise and plain a manner as possible the 

 action of the organs of fertilization in our commonest native species, 

 Orchis onascula, and at the same time briefly pointing out some of 

 the differences which exist between it and other members of the 

 family. The accompanying illustrations, without which we find it 

 almost impossible to convey a clear description of the method of 

 fertilization, have been kindly drawn and lent to me by E. C. 

 Malan, M.A., F.L.S., of Cheam, and represent the various parts of 

 the flowers of 0. mascula, much enlarged. In Fig. 1 (where we are 

 supposed to be looking direct into an open flower, the sepals and 

 petals of which, except the labellum, have been removed), above the 

 entrance to the nectary, which, as well as the ovarium, is here 

 hidden from view, and immediately under the pouch - formed 

 rostellum, will be seen the bi-lobed stigma, a surface so sticky as to 

 retain whatever substance comes in contact with it, such as dust, 

 small insects, or the properly-placed pollen. The anther, which 

 consists of two separate cells, each containing a pollen mass, or 

 pollinium, is situated above the rostellum. A pollen mass, or 

 pollinium (Fig. 2), consists of a number of pollen grains fastened 

 together by very elastic threads ; a caiidicle or footstalk ; and a 

 minute jDiece or disc of membrane with a ball of viscid matter on 

 the under side. The pollinia have separate discs and are enclosed 

 and kept moist by the rostellum. 



How this somewhat complex mechanism acts (and Fig. 3 will 

 serve to explain it), we will now describe in the words of Darwin : 

 " Suppose an insect to alight on the labellum, which forms a good 

 landing-place, and to push its head into the chamber (see side view 

 Fig. 3, or front view Fig. 1), at the back of which lies the stigma, 

 in order to reach with its proboscis the end of the nectary ; or which 

 does equally well to show the action, push very gently a sharply- 

 pointed common pencil into the nectary. Owing to the pouch-formed 

 rostellum projecting into the gangway of the nectary, it is scarcely 

 possible that any object can be pushed into it without the rostellum 

 being touched. The exterior membrane of the rostellum then 

 ruptures in the proper lines, and the lij) or pouch is easily depressed. 

 When this is effected, one or both of the viscid balls will almost 

 infallibly touch the . intruding body. So viscid are the balls, that 

 whatever they touch they firmly stick to. Moreover, the viscid 

 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 



