Cbap. VI]. MONACHAilTHUS VIRIDIS. 201 



remarkable manner from that of the male Gatasetum 

 tridentatum, and it is no wonder that the two plants 

 were formerly ranked as distinct genera. 



The pollen-masses offer so cnrious and good an illus- 

 tration of a structure in a rudimentary condition, that 

 they are worth description ; but I must first recur to 

 the perfect pollen-masses of the male Catasetum. 

 These may be seen at D and E, fig. 29, attached to 

 the pedicel : they consist of a large sheet of cemented 

 or waxy pollen-grains, folded over so as to form a 

 sack, with an open slit along the lower surface, within 

 which at the lower and produced end, a layer of highly 

 elastic tissue, forming the caudicle, is attached; the 

 other end being attached to the pedicel of the rostellum. 

 The exterior grains of pollen are more angular, have 

 thicker walls, and are yellower than the interior grains. 

 In the early bud the two pollen-masses are enveloped 

 in two conjoined membranous sacks, which are soon 

 penetrated by the two produced ends of the pollen- 

 masses and by their caudicles ; and afterwards the 

 extremities of the caudicles adhere to the pedicel. 

 Before the flower expands the membranous sacks in- 

 cluding the two pollen-masses open ; and the pollen- 

 masses are left resting naked on the back of the 

 rostellum. 



In Monachanthus, on the other hand, the two mem- 

 branous sacks containing the rudimentary pollen- 

 masses never open ; but they easily separate from each 

 other and from the anther. The tissue of which they 

 are formed is thick and pulpy. Like most rudi- 

 mentary parts, the pollen-masses vary much in size 

 and form; they are only about one-tenth of the bulk 

 of those of the male ; they are flask-shaped (p, fig. 31), 

 with the lower end greatly produced so as almost to 

 penetrate the exterior or membranous sack. There is 

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