220 THE ORCHIDACE^ OF THE 



by means of short threads of very elastic tissue into small masses, 

 and these into larger, and at length into pellets, having stalks of 

 the same elastic tissue, by which they are all attached to a firmer 

 central stalk, or caudicle. To the lower end of this caudicle 

 (directly to the end of it in our Hahenaria and Orchids generally) 

 is attached a button-shaped disc, the face of which is exposed, and 

 is on a line with the surface of the anther : so that these two 

 discs look toward each other across the broad stigmatic space 

 (PI. XXIII. , Fig. i). The exposed face of the disc being covered 

 with a durable layer of very viscid matter, the body itself is some- 

 times termed a gland. The viscidity is nearly of the same nature 

 as that of the intervening stigma, of which the glands are gener- 

 ally supposed to be detached portions. If so, then a portion of 

 the stigma is cut off from the rest and specialised for the purpose 

 of the conveyance of the pollen. When a finger's end or any 

 small body is appUed to these discs they adhere so firmly that 

 the attached pollinia or pollen-masses are dragged out of the 

 cell and carried away entire. 



Some of the pollen-masses have been found attached by the disc 

 to the eye of a large moth. When a moth of the size of head and 

 length of proboscis of Sphinx driipiferarum visits a spike of these 

 flowers, and presses its head into the centre of the flower, so that 

 its proboscis may reach and drain the nectariferous tube, a pollen- 

 mass will usually be affixed to each eye. On withdrawal these 

 will stand as in the accompanying iUustration (PL XXIII. , 

 Fig. 3). Within a minute, or according to that eminent naturalist, 

 the late Charles Darwin, in 30 seconds, they will be turned down- 

 wards (as in Fig. 4), not by their weight, but by a contraction in 

 drying of one side of the thick piece which connects the disc with 

 the stalk. When a moth in this condition passes from the last open 

 flower of one spike to that of another plant, and thrusts its proboscis 

 down a nectary, the transported pollen-masses will be brought in con- 

 tact with the large glutinous stigma ; on withdrawal, either some 

 of the small pellets of pollen will be left adherent to the stigma, 

 the connecting elastic threads giving way, or else a whole pollen- 

 mass will be so left, its adhesion to the glutinous stigma being 

 greater than that of the disc on the moth's eye. The former is a 

 common and economical proceeding, as then a succession of 



