Chai-. IX. 



GRADATION OF ORGANS. 



259 



tied together in the Ophreoe, and which run far up 

 inside the waxy masses of the Vandefc, are also of a 

 different nature from the cementing matter ; for the 

 threads are acted on by chloroform and by long im- 

 mersion in spirits of wine ; whilst these fluids have no 

 jjarticular action on the cohesion of the waxy masses. 

 In several Epidendrea? and Vandeae the exterior grains 

 of the pollen-masses differ from the interior grains, in 

 being larger, and in having yellower and much thicker 

 walls. So that in the contents of a single anther-cell 

 we see a surju-ising degree of differentiation in the 

 pollen, namely, grains cohering by fours, then being 

 either tied together by threads or cemented together 

 into solid masses, with the exterior grains different 

 from the interior ones. 



In the Vandea3, the caudicle, which is composed of 

 fine coherent threads, is developed from the semi-fluid 

 contents of a layer of cells. As I find that chloroform 

 has a peculiar and energetic action on the caudicles 

 of all Orchids, and likewise on the glutinous matter 

 which envelopes the pollen-grains in Cypripedium, 

 and which can be drawn out into threads, we may 

 suspect that in this latter genus, — the least differenti- 

 ated in structure of all the Orchideae, — we see the 

 ju'imordial condition of the elastic threads by which 

 the pollen-grains are tied together in other and more 

 highly developed species.* 



* Auguste de Sfaint Hilairo 

 {' Lt'(;ons de Botanique,' &c., 1841, 

 ]>. 447) says that the elastic threads 

 exist ill the early bud, after the 

 pollen-grains have been partly 

 tbiiiiod, as a thick creamy fluid. 

 He adds tliat his obseivatious on 

 (Jp]iri/>i ajji'fcra have shown him 

 tlint this fluid is secreted by the 

 ro^tellum, and is slowly forced 



drop by drop into the anther. 

 Had not so eminent an authority 

 made this statement, I should not 

 have noticed it. It is certainly 

 erroneous. In buds of Epipactis 

 latifoUa I opened the anther, 

 whil.st perfectly closed and free 

 fiom the rostellum, and found the 

 pollen-grains united by elastic 

 threads. Cephalunthcra grandi' 



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