100 



ON THE GENERAL ANALOGY OF 



and succulent flower, eaten as a luxury by the Hottentots, and parasitic to 

 the roots of the euphorbia mauritanica ; flower propagating flower from 

 generation to generation. 



But perhaps the plant most decisive upon this subject is the aerial epiden- 

 drum,* first, if I mistake not, described by that excellent Portuguese phytolo- 

 gist Loureiro, and denominated aerial from its very extraordinary properties. 

 This is a native of Java and the East Indies beyond the Ganges ; and, in the 

 latter region, it is no uncommon thing for the inhabitants to pluck it up, on 

 account of the elegance of its leaves, the beauty of its flower, and the exqui- 

 site odour it difi'uses, and to suspend it by a silken cord from the ceilings of 

 their rooms ; where, from year to year, it continues to put forth new leaves^ 

 new blossoms, and new fragrance, excited alone to new life and action by the 

 stimulus of the surrounding atmosphere. 



That stimulus is oxygen; ammonia is a good stimulus, but oxygen pos- 

 sesses far superior powers, and hence without some portion of oxygen few 

 plants can ever be made to germinate. Hence, too, the use of cow-dung and 

 other animal recrements, which consist of muriatic acid and ammonia : while 

 in fat, oil, and other fluids, that contain little or no oxygen, and consist 

 altogether, or nearly so, of hydrogen and carbon, seeds may be confined for 

 ages without exhibiting any germination whatever. And hence, again, and 

 the fact deserves to be extensively known, however torpid a seed may be^ 

 and destitute of all power to vegetate in any other substance, if steeped in a 

 diluted solution of oxygenated muriatic acid, at a temperature of about 46° or 

 48° of Fahrenheit, provided it still possess its principle of vitality, it will ger- 

 minate in a few hours. And if, after this, it be planted, as it ought to be, in 

 its appropriate soil, it will grow with as much speed and vigour as if it had 

 evinced no torpitude whatever. 



I have said that few plants can be made to germinate when the oxygen is 

 small in quantity, and the hydrogen abundant : and I have made the limita- 

 tion, because aquatic plants, and such as grow in marshes, and other moist 

 places, are remarkable, not only for parting with a large quantity of oxygen 

 gas, but also for absorbing hydrogen gas freely ; and are hence peculiarly 

 calculated for purifying the regions in which they flourish, and in some sort 

 for correcting the mischief that flows from the decomposition of the dead 

 vegetable and animal materials that is perpetually taking place in such situa- 

 tions, and loading the atmosphere with febrile and other miasms. 



But the instances of resemblance between animal and vegetable physiology 

 are innumerable. Some plants, like a few of our birds, more of our insects^ 

 and almost all our forest beasts, appear to sleep through the day, and to 

 awake and become active at night: while the greater number, like the greater 

 number of animals, resign themselves to sleep at sunset, and awake rein- 

 vigorated with the dawn. Like animals, they all feel the living power excited 

 by small degrees of electricity, but destroyed by severe shocks ; and like ani- 

 mals, too, they difl'er in a very extraordinary degree in the duration of many 

 of their species. Some tribes of boletus unfold themselves in a few hours, 

 like the ephemera and hemerobius tribes (May-fly and Spring-fly), and as 

 speedily decay. Several of the fungi live only a few days ; others weeks or 

 months. Annual plants, like the greater part of our insects, live three, four, 

 or even eight months. Biennial plants, like the longer-lived insects, and 

 most of our shell-fishes, continue alive sixteen, eighteen, or even twenty-four 

 months. Many of the herbaceous plants continue only a few years, but more 

 for a longer period, and imitate all the variety to be met with in the greater 

 number of birds, quadrupeds, and fishes ; while shrubs and trees are, for the 

 most part, coequal with the age of man, and a few of them equal that allotted 

 to him in the earliest periods of the world. Of these last, the Adansonia 

 digitata, or calabash tree,, is perhaps one of the most extraordinary. Indi- 

 genous to the land of the patriarchs, and still outrivalling the patriarchal age, 

 this stupendous tree, compared with which our own giant oak, in bulk as well 



* Epldendrum^s aeris. 



