BEES AS FERTILISERS. 



319 



and I was asked to name the disease which had caused 

 an abnormal outgrowth upon its head. It had visited, 

 there can be little doubt, an orchid-house, and had 

 carried away a decoration from one of the Vandese. 

 The description given above applies to Orchis 

 mascula, fusca, maculata, and latijolia, as well as 

 Aceras anthropophora (the man orchis), in all of which 

 the pollinia undergo the same curious movements of 

 depression which are necessary to enable them to 

 strike the stigmatic surfaces. The behaviour of these 

 British specimens is quite commonplace, however, in 

 comparison with that of some exotic orchids explained 

 by the genius of Darwin. A few words in reference 

 to one will suffice. In Catasetum, the genders are 

 divided, and the male blossom is provided with a 

 strange pair of long additions, called by Darwin "the 

 antennae." In some species both are equally active, 

 but in others the right one seems functionless, while 

 the left is intensely irritable, and, should an insect 

 touch it, a vibration is transmitted to a certain mem- 

 brane, which is instantly ruptured, and so sets free 

 the pollen mass, which is shot forth from the extremity 

 of a liberated spring, viscid end first, to attach itself 

 to the back of the insect. The startled bee flies, 

 possibly, to the female flower, and here accomplishes 

 a cross ; this act being favoured by the curious habit 

 of the Apidx of visiting one kind of flower only, 

 during any single excursion — a habit for which no 

 sufficient explanation can be given, although it will 

 receive further notice hereafter. Sir John Lubbock says : 

 "On one occasion, Darwin touched a male catasetum 

 in my presence, when the pollinium was thrown nearly 



