The Sex and Generative Organs of Plants. 267 



the upper and under surface of the leaf, undergoes a pecu- 

 Har swelhng and puckering up, and the nutritious juice con- 

 tained in it, runs together in each cell into a few, generally 

 four excessively small granules. These granules get more and 

 more thickened, and form themselves into the pollen. The 

 exceedingly delicate cells, called collenchyma, in vi^hich this 

 new formation takes place, are by degrees absorbed, and 

 at last disappear entirely, so that the small globules in the 

 form of a very fine dust lie free between the layers of the 

 anther, until 'at last after their pouch is torn, they issue out 

 of their cavity, and commence their generative functions 

 as male semen. If this pollen be now examined, we find 

 that its granules, which form innumerable round elliptic 

 or angular bodies, are small bladders formed of a double 

 skin. The outer coat is the stronger, and is frequently 

 evidently composed of very small cells ; nevertheless in this 

 case also it is apparently to be regarded as a simple cell, 

 whose surface is strengthened by a net-like thickening. The 

 inner coat touches the other on its inner surface, and is ex- 

 ceedingly delicate, and almost transparent. The outer coat 

 has a considerable power of self-contraction, is at particular 

 points provided with folds or pores, and at times separates it- 

 self partially from the inner one. The latter is very thin, and 

 on fecundation issues out at particular places ; namely, at the 

 pores or folds of the outer skin. We now easily recognize 

 that it is filled with a very delicate slimy fluid, in which 

 exceedingly minute corpuscles of round or oblong form 

 swim, moving themselves about frequently and actively. 

 This delicate fluid (fovilla) corresponds to the fecunda- 

 ting fluid in animal semen. The inner coat of the pollen 

 granule lengthens itself in the act of fecundation into the 

 form of an exceedingly fine transparent tube, which now 

 continues its growth, until it has reached the part which we 

 view, under the name of the vegetable ovum, as the future 

 depository of the semen. 



