VII.] 



ORCHIS. 



173 



base of the proboscis into contact with the two 

 viscid disks, which at once adhere to it, so that when 

 the insect draws back its proboscis, it carries away 

 the two pollen masses. It is easy to imitate this with 

 a piece of grass, and to carry away on it the two 

 pollen masses and their stalks. If, however, the 

 pollinium retained this erect position when the insect 

 came to the next flower, it would simply be pushed 

 into or against its old position. Instead, however, of 

 remaining upright, the pollinia, by the contraction of 

 the minute disk of membrane to which they are 

 attached, gradually turn downwards and forwards, 

 and thus when the insect sucks the next flower, the 

 thick end of the club exactly strikes the stigmatic 

 surfaces (st st). The pollinium or pollen-mass consists 

 of packets of pollen grains, fastened together by 

 elastic threads. The stigma, however, is so viscid, 

 that it pulls off some of these packets, and ruptures 

 the threads, without removing the whole pollinium, 

 so that one pollinium can fertilise several flowers. 



This description applies in essentials not only to 

 Orchis mascula, but also to O. Morio, O. fusca, O. 

 maculata, and O. latifolia, as well as to Aceras 

 anthropophora (the Man orchis), in all of which 

 the pollinia undergo, after removal from the anther 

 cells, the curious movement of depression, which is 

 necessary in order to place them in the right position 

 to strike the stigmatic surface. 



0. pyramidalis differs from the above group in 

 several important points. The two stigmatic surfaces 

 are quite distinct, and the rostellum is brought down, 

 so as to overhang and partly close the entrance to the 

 nectary. The viscid disks which support the pollen 



