414 PROPAGATION OF THE SPECIES. CHAP. IX, 



always proves abortive and falls, tending only to 

 nourish the other ; but in the case of the ad- 

 herence of other acknowledged seeds, as in that of 

 Daleciy Lagtfcia, Hasselquestia, and others, the abor- 

 tive seed does not fall, but still continues adherent. 



Having thus pulled to pieces the hypothesis of 

 Gaertner, the next object of Mr. Correa is to es- 

 tablish his own namely, that the mucous substance 

 surrounding the grains of the plants in question 

 is a true pollen. If this, he adds, is found to be 

 contrary to the character of the pollen of terrestrial 

 plants, so, it should be remembered, is the medium 

 through which it has to pass; and if it should be 

 said that the pollen of some aquatics, such as Po- 

 tamogeton and Vallimeria is still powdery, it is to 

 be recollected that their flowers emerge above water 

 at the season of fecundation ; or if there are any 

 aquatics which do not emerge and have yet a powdery 

 pollen, it should be recollected that the process takes 

 place wholly under cover, as in the case of Zostera, in 

 which the flower is situated in the cavity of the stem, 

 and does not open till fecundation is over : and even 

 in plants vegetating in the open air, nature em- 

 ploys various expedients to preserve the pollen 

 from wet. 



But it is not absolutely necessary that the pollen 

 should be farinaceous even in terrestrial plants, or 

 rather it is known and acknowledged that this is not 

 always so. In the Orchidea it consists of a mass of 

 solid particles, assuming in the aggregate a sort of 



