258 GRADATION OF ORGANS. Chap. IX 



single grains are embedded in a glutinous fluid ; in 

 all the other Orchids seen by me (except the degraded 

 Oephalanthera) the grains are united three or four 

 together.* 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 Epidendreae and 

 Vandese from eight to four, to two, and, by the co- 

 hesion of the two, into a single mass. In some of the 

 Epidendrese 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. 

 1'he elastic threads by which the packets of pollen are 



* In several cases I have ob- tubes are, at least at first, formed 



served four tubes emitted fiom exclusively at the expense of the 



the four giains which form one of contents of the pollen -grains, 



the compound grains. In some Having alluded to the monstrous 



senii-m.onsttous flowers of Ma/aa-/.s flowers of the Aceias, I will add 



paludosa, and of Aceras anthropo- thai I examined several (always 



phora, and in perfect flowers of the lowest on the spike) in which 



JSeottia nidus-avis, i have observed the labellum was hardly developed, 



tubes emitted from the pollen- and w^as pressed close agninst the 



grains, whils^t still within the stigma. The mstellum was not 



anther and not m contact with developed, so that the polliida did 



the fctigma. I have thought this not possess viscid discs ; but the 



worth mentioning as R. Brown most curious feature was, that the 



(' Linn. Transact.' vol. xvi. p. 729) two anther-cells had become, appa- 



states, apparently with some sur- rently in consequence of the post- 



prise, that the pollen-tubes wt re tion of the rudimentary labellum. 



eniitted from the pollen, whilst widely separated, and were joined 



Htill within the anther, in a decay- by a connective membrane, almost 



ing flower of Asclcpias. These as broad as that of Haheiiaria 



tases show that the protruding ddoraiitha J 



