single grains are embedded in a glutinous fluid; in all the other Orchids seen by me (except the degraded Cephalanthera) the grains are united three or four together.[1] These compound grains are tied one to the other by elastic threads, but they often form packets which are tied together in like manner, or they are cemented into the so-called waxy masses. The waxy masses graduate in the Epidendreæ and Vandeæ from eight to four, to two, and, by the cohesion of the two, into a single mass. In some of the Epidendreæ we have both kinds of pollen within the same anther, namely, large waxy masses, and caudicles formed of elastic threads with numerous compound grains adhering to them.
I can throw no light on the nature of the cohesion of the pollen in the waxy masses; when they are placed in water for three or four days, the compound grains readily fall apart; but the four grains of which each is formed still firmly cohere; so that the nature of the cohesion in the two cases must be different. The elastic threads by which the packets of pollen are
- ↑ In several cases I have observed four tubes emitted from the four grains which form one of the compound grains. In some semi-monstrous flowers of Malaxis paludosa, and of Aceras anthropophora, and in perfect flowers of Neottia nidus-avis, I have observed tubes emitted from the pollen- grains, whilst still within the anther and not in contact with the stigma. I have thought this worth mentioning as K. Brown ('Linn. Transact.' vol. xvi. p. 729) states, apparently with some surprise, that the pollen-tubes were emitted from the pollen, whilst still within the anther, in a decaying flower of Asclepias. These cases show that the protruding tubes are, at least at first, formed exclusively at the expense of the contents of the pollen-grains.
Having alluded to the monstrous flowers of the Aceras, I will add that I examined several (always the lowest on the spike) in which the labellum was hardly developed, and was pressed close against the stigma. The rostellum was not developed, so that the pollinia did not possess viscid discs; but the most curious feature was, that the two anther-cells had become, apparently in consequence of the position of the rudimentary labellum, widely separated, and were joined by a connective membrane, almost as broad as that of Habenaria clorantha!
