350 IMPREGNATION OF THE SEED. CHAP* VII. 



of the embryo, constituting a nucleus, is perceptible 

 in the seed, then also the pollen appears, but the 

 flower has no beauty. And when the embryo is 

 found no longer constituting a mere nucleus, but 

 surrounded with its cotyledons, then there is to be 

 seen both the apparatus of flower and of sexual 

 organs. The first class includes plants without 

 sex, the Conferva, Ulv<z, Fungi. The second 

 class includes the Approdites, the Filices, Musci, 

 Fuel. The third class includes what are called 

 ambiguous plants, such as Zostera, Zamia, Cycas. 

 And the fourth class includes all plants whatever 

 with conspicuous flowers. This gradation, if not 

 true, is at least beautiful ; and will perhaps be ad- 

 mitted to be also useful ; from which we may infer 

 the truth of the observation that even the very 

 errors of a great mind are edifying. 



CHAPTER VII. 



OF THE IMPREGNATION OF THE SEED. 



ADMITTING that the stamens and pistils are the 

 male and female organs of vegetable generation, 

 and that the pollen is the substance by which the 

 impregnation of the seed is eiFected, how is it 

 conveyed to the ovary ? and what is the amount 

 of its action ? 



