74 ANATOMY OF THE TREE PRIMROSE. 



I found an anther to consist of two longitudinal cells, A A, Fig. 1, 

 filled with ripe pollen, held in suspension by an exceedingly small 

 quantity .of a highly tenacious fluid, strongly resembling that from 

 which the spider spins his web, and which, when the particles of pollen 

 were disturbed, and adhered to my instruments, became drawn out 

 with them into inconceivably fine films. These cells were separated 

 by a vascular and transparent partition B, terminating at each end in 

 the two glands C C, and prominent at the back of the anther, at E, 

 Fig. 2. The liquid they contained was conveyed up the filament D, 

 into the small gland F, and the principal part of it, after supplying the 

 partition, was secreted in the large glands, C C, Fig. 1. This liquid 

 has, however, the peculiar quality of drying as soon as exposed to the 

 air, or rather, perhaps, of evaporating ; for the perfectly ripe pollen is, 

 to all appearance, as dry as that of any other plant. It is therefore, 

 it would appear, intended for the purpose of keeping the particles to- 

 gether, but so slightly, that the elasticity and spring with which the 

 petals fly open is sufficient to disperse the pollen on the stigma, and 

 the superfluous particles adhere to the films produced by the fluid, in 

 all directions, between the stigma and the anthers. Whether the 

 anthers are originally continuous round vessels, which burst when the 

 pollen is ripe, either lengthwise or otherwise, or whether they are 

 merely open cells in which the pollen is lodged, I have not been able 

 to discover; but from the peculiar office of the tenacious fluid, and the 

 circumstance of their shrivelling up immediately after the pollen is 

 discharged, I am rather inclined to think the latter is the fact. In 

 dissecting one of the anthers, I separated a membranaceous thread or 

 nerveTrom its side, which I thought exhibited a kind of involuntary 

 oscillatory motion ; but this might only be the effect of the air. Should 

 it however prove otherwise, it is no doubt intended to assist the dis- 

 persion of the pollen. This circumstance of the peculiar structure of 

 the anthers, and also the tenacious fluid which holds the pollen, renders 

 it important that the flower should blow in the evening, as the heat of 

 the sun in the day would dry up the fluid, and thus prevent the proper 

 dispersion of the pollen. 



It would be worth investigating, whether the same circumstances 

 attend the night-blowing cereus (Cactus grandiflora, 



Liverpool Road, Islington, tlth Nov., 1832. 



