ORCHIDACE^. 89 



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

 proboscis or pencU in the course on an average of tliirty seconds. Now after this 

 movement and the interval of time which would allow the insect to fly to another 

 flower, it ^vill be seen that if the pencil be inserted into the nectary, the thick end of 

 the pollen-bag will exactly strike the stigmatic surface. Here again comes into play 

 another pretty adaptation, long ago noticed by Robert Brown. The stigma is very 

 viscid, but not so viscid as when touched to pull the whole pollen-bag off the insect's 

 head or off the pencil, yet sufficiently viscid to break the elastic threads by which the 

 packets of pollen-grains are tied together and leave some of them on the stigma. 

 Hence a poUen-bag attached to an insect or to the pencil can be applied to many 

 stigmas and will fertilise all. I have seen the poUen-bag of Orchis pyramidaUs 

 adhering to the proboscis of a moth, with the stump-like caudicle alone left, all the 

 packets of poUen having been left glued to the stigmas of the flowers successively 

 visited. One or two little points must still be noticed. The balls of viscid matter 

 within the pouch- formed rostellum are surrounded with fluid ; and this is very impor- 

 tant, for, as already mentioned, the viscid matter sets hard when exposed to the air 

 for a very short time. I have pulled the balls out of their pouches, and have found 

 that in a few minutes they entii-ely lost their power of adhesion. Again, the little 

 discs of membrane, the movement of which as causing the movement of the pollen- 

 bags is so absolutely indispensable for the fertilisation of the flower, lie at the upper 

 and back surface of the rostellam, and are closely enfolded and thus kept damp 

 within the bases of the anther-cells ; and this is very necessary, as an exposure of about 

 thirty seconds causes the movement of depression to take place ; but as long as the 

 disc is kept damp the pollen-bags remain ready for action whenever removed by an 

 insect. Lastly, as I have shown, the pouch after having been depressed spiings up to its 

 former position, and this is of great ser\'ice ; for, if this action did not take place, and 

 an insect after depressing the Hp failed to remove either viscid baU, or if it removed 

 one alone, in the first case both, and in the second case one of the viscid balls would 

 be left exposed to the air. Consequently they would quickly lose all adhesiveness, 

 and the poUen would be rendered absolutely useless. That insects often remove one 

 alone of the two pollen-bags or poUinia at a time in many kinds of orchis is certain ; 

 it is even probable that they generally remove only one at a time, for the lower and 

 older flowers almost always have both pollen-bags removed, and the younger flowers 

 close beneath the buds, which wiU have been seldomer visited, have frequently only 

 onepollininm removed. In a spike of Orchis maculata I found as many as ten flowers, 

 chiefly the upper ones, which had only one pollinium removed ; the other polhnium 

 being in place, with the lip of the rostellum well closed up, and all the mechanism 

 perfect for its subsequent removal by some insect." The nectary of Aceras anthropo- 

 phora, our present species, is very short. 



The British species of Orchis are mostly red or lilac in colour, sometimes white or 

 green, and often beautifully mottled. With the exception of the green ones, all seem 

 capable of the albino condition, and there are few that do not exhale perfume, espe- 

 cially in the evening ; many kinds are, however, very capricious in this respect. 

 They grow in woods, meadows, and pastures, in marshes, upon hills, and on grassy 

 banks exposed to the splash of the sea ; the insectiform species, however, are almost 

 entirely confined to chalk and limestone. For the microscope they furnish, in all 

 their pa.ts, very beautiful objects. The green flowers of the species mentioned above 

 present the figure of a little man " swinging as if some great ogre held In'm by tho 

 Lair of his head." 



VOL. IX. N 



