22 Revieics. — Lindlcy^s Theory of Horliculturc. 



follows, as a necessary consequence, that the natural habits of nn 

 unknown |)lant may be judged of with considerable certainty by a 

 niicrosco[)ioal examination of the structure of its epidermis. The 

 rule will evidently be, that plants with a thick epidermis, and only a 

 few small stomates, will be the inhabitants of situations where the 

 air is dry and the su])ply of liquid food extremely small; while those 

 with a thin epidermis, and a great nundjer of large stomates, will be- 

 long to a cliuiate damp and humid; and intermediate deirrees of 

 structure will indicate intermediate degrees of atmospherical and 

 lerrestial conditions. It is, however, to be observed, that the rela- 

 tive si:e of stomates is often a more important mark in investiga- 

 tions of this nature than their number; those organs being in many 

 plants extremely immerous, but small and apparently capable of ac- 

 tion in a very limited degree; while in others, where they are much 

 less numerous, they are large and obviously very active organs. 

 Thus the numl)er of stomates in a square inch of the ei)iderniis of 

 Crinum amabile is estimated at 40,000, and in that of Mesembry- 

 anthemuni at 70,000, and of an Aloe at 45,000; the first inhabiting 

 the damp ditches of Intlia, the last two natives of the dry rocks of 

 the Cape of Good Hope: but the stomates of Crinum amabile are 

 among the largest that are known, and those of Mesembryantheinutn 

 and Aloe are among the smallest; so that the 70,000 of the former 

 are not equal to 10,000 of the Crinum. Again, the Yucca aloifolia 

 has four times as many stomates as a species of Cotyledon in my 

 collection, but those of the latter are about the one seven hundred 

 and fiftieth of an inch in their longer diameter, large and active, 

 while the stoinates of the Yucca are not more than one two thousand 

 and five hundredth of an inch long in the aperture, and comparativt ly 

 inert. The Yucca, therefore, with its numerous stomates, has 

 weaker powers of perspiration and resi)iration than the Cotyledon. 



There are some of a sickly sensibility, who are perpetually 

 ringing changes on the gloomy realities of life, and endeavor- 

 ing to find in the economy of nature, soitie seeming proof or 

 illustration. Autuinn in its varied dyes, the changing, droop- 

 ing leaf, returning to the bosom of the earth to moulder and 

 decay, are brought into their aid by way of poetic effect. 

 With such ideas we confess we have no sympathy. V/hat 

 beauty ever invests this earth — what curious, wondrous trans- 

 formation! The dry leaf "eddying in the blast," h;is con- 

 summated its work. 'T is no longer an organ of an organized 

 fabric endued with vital energy, but 't is still a beauteous thing. 

 Obedient to the fiat of nature, it will again enter into new 

 combination and renewed beauty. 



In the course of time, a leaf becomes incapable of performing its 

 functions; its passages are choked up by the deposit of sedimentary 

 matter; there is no longer a free communication between its paren- 

 chyma and that of the rind, or between its veins and the wood and 

 liber. It changes color, ceases to decompose carbonic acid, absorbs 



