258 GEADATION OF ORGANS. Chap. IX. 



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.* 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 Epidendrese 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. 

 The elastic threads by which the packets of pollen are 



* 111 peveral cases I have ob- tubes are, st least at first, formed 



served four tubes emitted from exclusively at the expense of the 



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



the compound grains. In somo Havingalludedtothemonstroug 



temi-monstrous flowers of Malaxis flowers of the Aceias, I will add 



paltidosa, and ol Aceras anthropo- that I examined several (always 



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



Neottia nidus-avis, 1 have observed the labellum was hardly developed, 



tubes emitted from the pollen- and was pressed close agiiinst the 



grains, whil&t still within the stigma. The rnstellum was not 



anther and not in contact with developed, so that the poIUiiia did 



the stigma. I have thought th s not possess viscid discs ; but the 



worth mentioning as B. 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 wi re tion of the rudimentai'y labellum. 



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



ftill within the anther, in a deca.\ - by a connective membrane, almost 



ing flower of Asolepias. These as broad as that of Habenarin 



cases show tliat the protrudii'j, cMorantJiaJ 



