Natural History, fyc. 637 



submerged leaves have no need of protection from rapid evaporation, 

 nor of any mechanical contrivance by which a too active influence 

 might be exerted upon them by the atmosphere ; and besides, the at- 

 mospheric air by which they are to be acted upon is itself dissolved 

 in the circumambient water. Hence such leaves have no cuticle. 



With regard to the stomata, the author shews, by various observa- 

 tions, that the common opinion, of there being openings through the 

 cuticle into the cavernous parenchyma of the leaf, is just ; and con- 

 sequently, that they are not closed up by a membrane, as is the 

 opinion of Turpin and Raspail, and as has been more recently stated 

 by Mr. Brown. His best proof of this is that which he has drawn 

 from an inspection of very young unexpanded leaves of the Narcissus 

 and Lily, examined near the bulb. In these the stomata are circular 

 evident perforations, surrounded by a circular elevated rim. The 

 paper, which is published in the A /males des Sciences for December 

 last, is accompanied by highly magnified drawings. 



3. GERMINATION OF SEEDS AT THE SURFACE OF MERCURY. 



Some experiments have been instituted by Professor Mulder to de- 

 termine the force with which roots are developed. He placed seeds 

 of the bean and buckwheat in glasses containing mercury, covered 

 over with water, laying them upon the surface of the mercury, and 

 taking care that they were just about to germinate. The very next 

 day the beans had forced their radicles into the mercury ; but those 

 of the buckwheat ran along the surface, forming a sort of net- work 

 by their interlacing, and not making the smallest impression upon 

 the mercury. This experiment was instituted on the 26th of Sep- 

 tember ; on the 26th of October he found many of the bean-roots 

 had ramified beneath the mercury, between it and the sides of the 

 glass ; but what was especially worthy of remark, in every instance 

 the root was curved back upon itself in the water at its origin. 

 Hence the author concludes, that there is an internal force which 

 propels the roots, and which, while it sometimes yields to external 

 circumstances, is never wholly destroyed. 



4. FERTILIZATION OF PLANTS. 



M. Amici has lately indicated a simple mode of witnessing the man- 

 ner in which the fertilization of vegetables takes place. When M. 

 Adolphe Brongniart published his opinions upon this subject he 

 asserted that, upon the bursting of a grain of pollen, an internal very 

 delicate membrane is protruded, which acts as a boyau, or sheath, 

 to the vivifying particles that are emitted, and which insinuates itself 

 between the cellules of the tissue of the stigma, thus establishing the 

 ingress of the fertilizing matter into the system of the ovarium. It 

 has since been a common opinion, that M. Brongniart was, in that 

 respect, deceived by some optical illusions, and that the sheath or 

 boyau in question has no existence. The object of M. Amici is to 



