Chap. VI. MOVEMENTS OF THE POLLINIA. 155 



very oddly shaped; and as the stigmatic chamber 

 is deep and likewise curiously shaped, we are led to 

 believe that the disc is fastened with great precision 

 to the square projecting head of some insect.* 



In most eases there is a plain- relation between the 

 length of the pedicel and the depth of the stigmatic 

 chamber, into which the pollen-masses have to be 

 inserted. In some few cases, however, in which a long 

 pedicel and a shallow stigma co-exist, we shall presently 

 meet with curious compensating actions. After the 

 disc and pedicel have been removed, the shape of the 

 remaining part of the rostellum is of course altered, 

 being now slightly shorter and thinner, and sometimes 

 notched. In Stanhopea, the entire circumference of 

 the extremity of the rostellum is removed, and a thin, 

 pointed, needle-like process alone is left, which origin- 

 ally ran up the centre of the disc. 



If we now turn to the diagram (fig. 23, p. 150), and 

 suppose the rectangularly bent rostellum to be thinner 

 and the stigma to lie closer beneath it than is there 

 represented, we shall see that, if an insect with a poUi- 

 nium attached to its head were to fly to another flower 

 and occupy exactly the same position which it held 

 whilst the attachment was effected, the pollen-masses 

 would be in the right position for striking the stigma, 

 especially if, from their weight, they were to become 

 in the least degree depressed. This is all that takes 

 place in Ly caste skinnerii, ■ Cymhidiwm giganteum, 

 Zygopetalum mackai, Angrseoum ebarneum, Miltonia 

 clowesii, in a Warrea, and, I believe, in Galeandra 

 funJcii. But if in our diagram we suppose, for instance, 



* I may here remark that Del- dium, Epidendrum, Phams, and 



pino (' Fecondazione nelle Piante,' Dendrobium, and is able to eon- 



Firenze, 1867, p. 19) says he has firm in general my statements, 

 examined flowers of Vanda^ Onci- 



