390 The Ways of the Orchids. 



pollen grains are fastened, but it leaves others for another 

 flower to catch in turn. This description applies, especially 

 to 0. maculata, and similar flowers, but it affords the key 

 to the process which takes place throughout the tribe. In 

 0. pyramidalis the viscid disc is single and saddle-shaped, and 

 the labellum, or lip leaf, is furnished with two ridges " expand- 

 ing outwards like the mouth of a decoy/' and which will guide 

 any fine flexible body to the trap which the plant contains. 

 The proboscis of a moth, or a bristle, in an artificial experiment, 

 finds itself saddled with the adhesive disc, and Mr. Darwin 

 gives a drawing of the head of an Acantia luctuosa, to whose 

 proboscis seven pairs of pollinia are attached. 



There is a highly interesting question of orchid manners 

 not quite solved, although an explanation suggested by Darwin 

 appears likely to prove true. In many orchids no secreted nectar 

 has been discovered, and it was supposed that they were the 

 Jeremy Diddlers of the vegetable world, existing by an " orga- 

 nized system of deception." Mr. Darwin chivalrously endea- 

 vours to rescue their morality from so odious a charge, which 

 likewise impugns the sagacity of countless generations of moths, 

 and, after sundry experiments, he arrived at the conclusion that 

 the insects have to bore through a delicate membrane to arrive 

 at the treasured sweets, and that this delay gives the adhesive 

 matter of the discs time to set. In five species he found the 

 honied bait within the nectaries, and in them the cement 

 solidified so quickly that the plant had no need to detain its 

 useful guest. 



In the genus Ojohrys, important varieties of structure are 

 met with, and the motive of the insects for visiting the flowers 

 is not clear, but, nevertheless, their curious intervention is 

 proved to take place. In another great tribe of British orchids, 

 the Neottece, a new set of difficulties, and special arrangements 

 to overcome them, appear. Thus, in the Marsh Epispactis an 

 insect could enter without touching the rostellum, but when 

 once inside the labellum would spring up, and he would have 

 to back out, and place himself in the right positon for the 

 rostellum to fit him with a membranous cap, bearing the pol- 

 len grains. In the Ladies' Tresses, spiranthes autnmnalis, the 

 rostellum is "a long, thin, flat projection/' bearing in its 

 middle what Mr. Darwin terms the " boat-formed disc." The 

 touch of an insect's proboscis, the vapour of chloroform, or a 

 natural change in the condition of the plant, splits a fine mem- 

 brane, and sets the apparatus free. 



In three genera of British orchids, the Malaaris, I/isb&ra, 

 and Neottca, "no portion of the exterior membranous surface 

 of the rostellum is permanently attached to the pollinia." 

 The first we shall pass over, but the second introduces us to 



