Chap. IX. GRADATION OF ORGANS. 259 



tied together in the Ophrese, and which run far up 

 inside the waxy masses of the Vaudeae, 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 

 particular action on the cohesion of the waxy masses. 

 In several Epidendrese and Vandeas the exterior grains 

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

 being larger, and in having yellower and much thickei 

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

 we see a surprising 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 VandesB, the caudiele, 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 Cypripediixm, 

 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 Orchidese, — we see the ; 

 primordial condition of the elastic threads by which 

 the pollen-grains are tied together in other and more ; 

 highly developed species. * < 



• Auguste de Saint Hilniio drop by diop into the anther. 



('Leijons de Botanique,' &o.. 184', Had not so eminent an authority 



p. 447) says that the elastic threads made this statement, I should not 



exist in the early bud, after tlie have noticed it. It is certainly 



pollen-grains have been parlly erroneous. In buds of EpipactU 



formed, as a thick creamy fluid. latifolia I opened the anther. 



He adds that his observations on whilst perfectly closed and free 



Oplirys apifera have shown him from (he rostellum, and found the 



that this fluid is secreted by Ihe pollen-grains united by elastic 



rostellum, and is slowly forced threads. Cevhalanlhera graiidi- 



