398 On the Aeriferous Vesicles of the Utricularire. 



We thus see the utricles ph^y the part at once of organs of 

 respiration and of a hydrostatic apparatus. These organs there- 

 fore do not appear at a given moment and for a particuL'ir pur- 

 pose, but as a natural consequence of the anatomical structure 

 of the plant and the action of the surrounding medium. I 

 shall take the liberty of adding here a passage from a work by 

 Schleiden, already cited (Grundziige &c.)^ which relates to the 

 idea that I have just expressed : — 



"What is most interesting in the life of the plant/' says 

 Schleiden^ " is its dependence upon the life diffused over the 

 earth in general. It must be admitted that in the forces upon 

 which depend meteorological phenomena and the formation of 

 organs and of organisms [Bildungstrieh, &c.) we have already, as 

 given in a necessary manner, the cause which makes a certain 

 insect be produced during the flowering of a certain plant — an 

 insect the life of which depends in its turn npon its nutrition 

 by the nectar secreted by this plant ; then, in absorbing this 

 liquid, the insect transfers the pollen to the stigma, and thus 

 assures the continuance of the vegetable species which furnishes 

 it with its nourishment. When we consider the coincidence of 

 jdienomena for an isolated plant, it often appears to us to de- 

 pend upon pure chance ; for example, the coincidence of wind 

 with the flowering of the Abietineaj, of the fall of rain with that 

 of Amh'osinia Bassii'-^-, of the movement of the water with the 

 expansion of the flowers of Valisneria ; but these coincidences 

 are only necessary consequences of the same primitive forces 

 which manifested themselves in the evolution of our planet." 



The totality of the forms in which life manifests itself upon 

 the earth during a given epoch appears to us thus like a magni- 

 ficent mosaic, of which the different pieces brought together 

 mutually determine their nature. 



* The spathe of Ambrosinia Bassii presents the form of a trough, and 

 thus swims on the surface of the water. Tlie spadix, which rises in this 

 spathe, divides it into two parts by means of a membranous wing which 

 surrounds the spadix and is attached to the s])athe ; the lower compart- 

 ment contains the anthers, and the upper one a single ovary : between the 

 two com])artments there is a little aperture in the separating partition. 

 Fecundation cannot take place unless at the period oc ilowering rain falls 

 into the spathe. The water then tills the lower compartment, and its level 

 gradually rises uj) to the ovary in the upi)er compartment ; the pollen, 

 which floats on the surface of the water, thus comes in contact with the 

 organ which it has to fecundate. 



