184 DIFFtCIILTIES OF TMB THEORY 



fall from two secreting horns which stand above it; and 

 when the bucket is half-full, the water overflows by a spout 

 on one side. The basal part of the labellum stands over 

 the bucket, and is itself hollowed out into a sort of cham- 

 ber with two lateral entrances; within this chamber there 

 are curious fleshy ridges. The most ingenious man, if he 

 had not witnessed what takes place, could never have 

 imagined what purpose all these parts serve. But Dr. 

 Criiger saw crowds of large humble-bees visiting the gigan- 

 tic flowers of this orchid, not in order to suck nectar, but 

 to gnaw off the ridges within the chamber above the bucket; 

 in doing this they frequently pushed each other into the 

 bucket, and their wings being thus wetted they could not 

 fly awav, but were compelled to crawl out through the 

 passage "formed by the spout or overflow. Dr. Criiger saw 

 a " continual procession " of bees thus crawling out of their 

 involuntary bath. The passage is narrow, and is roofed over 

 by the column, so that a bee, in forcing its way out, first 

 rubs its back against the viscid stigma and then against the 

 viscid glands of the pollen-masses. The pollen-masses are 

 thus glued to the back of the bee which first happens to 

 crawl out through the passage of a lately expanded flower, 

 and are thus carried away. Dr. Criiger sent me a flower in 

 spirits of wine, with a bee which he had killed before it 

 had quite crawled out, with a pollen-mass still fastened to 

 its back. When the bee, thus provided, flies to another 

 flower, or to the same flower a second time, and is pushed 

 by its comrades into the bucket and then crawls out by the 

 passage, the pollen-mass necessarily comes first into con- 

 tact with the viscid stigma, and adheres to it, and the 

 flower is fertilized. Now at last we see the full use of every 

 part of the flower, of the water-secreting horns of the 

 bucket half-full of water, which prevents the bees from flying 

 away, and forces them to crawl out through the spout, and 

 rub against the properly placed viscid pollen-masses and 

 the viscid stigma. 



Tlie construction of the flower in another closely allied 

 orchid, namely, the Catasetum, is widely different, though 

 serving the same end; and is equally curious. Bees visit 

 these flowers, like those of the Coryanthes, in order to gnaw 

 the labellum; in doing this they inevitably touch a long, 

 tapering, sensitive projection, or, as 1 have called it, the 



