Chap. IX. GRADATION OF OKGANS. 259 



tied together in the Ophrese, and which run far up 

 inside the waxy masses of the Vandese, 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 EpidendresD and Yandeae 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 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 Vandeae, 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 Orchideee, — we see the 

 primordial condition of the elastic threads by which 

 the pollen-grains are tied together in other and more 

 highly developed species.* 



* Augnste de Saint Hilairo drop by drop into the anther. 



('Le(;ons de Botanique,' &&, 1S41, 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 the have noticed it. It is certainly 



pollen-grains have been partly erroneous. In buds of Epipactis 



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



He adds that his obsei-vations on whilst perfectly closed and free 



Ophrys api/era have shown him from the rostellum, and found the 



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



robtellum, and is slowly forced threads. Ceohalanthera grandi' 



