/ 



96 ON THE GENERAL ANALOGY OP 



already observed that some of them, and especially among the algag and 

 the mosses, are nearly altogether incombustible, as the byssus asbestos^ 

 which, on being thrown into the fire, instead of burning, is converted into 

 glass ; and the fontinalis antipyretica^ a plant indigenous to the Highlands, 

 but more frequent in Scandinavia, where from its difficulty of combustion 

 it is used by the poor as a lining for their chimneys to prevent them from 

 catching fire. 



Animals are often contemplated under the three divisions of terrestrial, 

 aquatic, and aerial. Plants may be contemplated in the same manner. 

 Among animals it is probable that the largest number consists of the first 

 division ; yet from the great variety of submarine genera that are known, 

 and from nearly an equal variety, perhaps, that are nnt known, this is un- 

 certain. Among vegetables, however, it is highly probable iKat the largest 

 number belongs to the Bubmarine section, if we may judge from the 

 almost countless species of fuci and other equally prolific tribes of an 

 aqueous and sub-aqueous origin, and the incalculable individuals that ap- 

 pertain to each species ; and more especially if we take into consideration 

 the greater equality of temperature which must necessarily exist in the 

 submarine hills and valleys. 



Many animals are amphibious, or capable of preserving life in either 

 element ; the vegetable world is not without instances of a similar power. 

 The algae, and especially in the ulva and fucus tribes, offer us a multitude 

 of examples. The juncus, or rush, in many of its species, is an amphi- 

 bious plant ; sO, too, is the oryza or rice-plant. In other words, all these 

 will flourish entirely covered with water, or with their roots alone shoot- 

 ing into a moist soil. 



. Animals of various kinds are aerial ; perhaps the term is not used with 

 strict correctness. It will, at least, apply with more correctness to plants. 

 All the most succulent plants of hot climates are of this description : such 

 are several of the palms and of the canes ; and the greater number of plants 

 that embellish the arid Karro fields of the Cape of Good Hope.* Suc- 

 culent as they are, these will only grow in soils or sands so sere and adust 

 that no moisture can be extracted from them, and are even destroyed by 

 a full supply of wet or by a rainy season. The Solandra grandijlora^ a 

 Jamaica shrub, was bng propagated in our own stoves by cuttings, which, 

 though freely watered, could never be made to produce any signs of fructi- 

 fication, notwithstanding that the cuttings grew several feet in length every 

 season. By accident a pot with young cuttings was mislaid and forgotten 

 in the Kew garden, and had no water given it ; it was hereby reduced to 

 its healthy aridity, and every extremity produced a flower. t 

 * And hence it is an opinion common to many of the ablest physiologists 

 of the present day, that these derive the whole of their nutriment from the 

 surrounding atmosphere ; and that the only advantage which they acquire 

 from thrusting their roots into such strata is that of obtaining an erect posi- 

 tion. There are some quadrupeds that appear to derive nutriment in the 

 same manner. Thus the bradypus tridactylus^ or sloth, never drinks, im- 

 bibes by its cutaneous absorbents, and trembles nt the feeling of rain ; and, 

 in common with the bird tribes, has only one ultimate or excrementary 

 duct ; while the olive cavy| avoids water of every kind almost as pertina- 



♦ The only rain that waters this tract is that which falls for a few weeks in the winter ; 

 during the hot and fertile months there is no rain whatever, 

 t Smith's Introdaction to Botany, &c. p, 141. 



I Cavia Acmcky. This is the more extraordinary, because the c. Cohaya, or Gwtaea- 

 pig, drinks freely; and the c. Ca;)i/6araj, or riyer cavy, is fond of swimming and divi^fg. 



