RHEUM RHINOCEROS. 



RHEUM (Linnaeus). A highly-valued genus of 

 fleshy-rooted herbs, all of which are medicinal, and 

 almost all of which are cultivated. The genus belongs 

 to Polygonacea. 



The cultivated rhubarb is in every garden, and 

 much more an object of the kitchen-gardener than 

 ever it was by the medical herbalist. It is now one 

 of our most favourite and useful vegetables, answering 

 the purpose of all kinds of baking or boiling fruit, 

 and at the most acceptable seasons, viz., throughout 

 the winter and spring months. 



Many new varieties have been raised from seed 

 prized for the immense size of their leaf-stalks, the 

 part used in cookery. No plant is easier of cultiva- 

 tion, and no one forced with less trouble. A new 

 sort, called the Goliah, is now very generally culti- 

 vated. The roots prepared for medical purposes are 

 chiefly imported from Turkey. 



RIIEXIA (Linnaeus). A genus of handsome 

 herbaceous plants, natives of America, and belonging 

 to the fine order Melastomacea. Whether potted or 

 in the open ground, they onlv succeed in peat-earth. 



RHINANTHUS. "A genus of annual plants, 

 natives of Europe, belonging to the natural order 

 ScropliularincE. Two of them are British, where they 

 are called " yellow-rattle ; " very common in every 

 damp meadow. 



RHINOCEROS (Rhinoceros). A genus of pachy- 

 dermatous mammalia, and one of the most singular of 

 the whole race singular as many of the rest are. 

 Though all the characters and most of the habits of 

 this genus of animals are very peculiar, yet the 

 " horn on the nose," on account of which the name 

 is given, and is merely the expression in Greek, is 

 certainly the most extraordinary part. It is a true 

 horn, and indeed more completely a horn than any 

 other appendage to which this name is given, as it 

 contains no sort of bone, and has no immediate con- 

 nection with the bones of the animal. When we say 

 " horn," in the case of these animals, we are to be 

 understood as speaking of the substance only ; for 

 most of the existing ones, as well as of those which 

 are now met with only in a fossil state, and generally, 

 if not exclusively, in places where none of the living 

 animals are met with, have two horns, generally a 

 large one and a smaller one, not placed laterally, but 

 in the rear of it, so that the centres of the bases of 

 both are on the mesial line and on the nose ; whereas 

 the horns of the other animals are on the forehead, 

 connected with the bones of the cranium, and in part 

 composed of prolongations of these. 



The nasal bones of the rhinoceros are strongly 

 formed and vaulted, and otherwise fortified for sup- 

 porting the base of the horn, but there is no imme- 

 diate connexion. The horn is altogether a production 

 of the skin, as is the case with all the heavy sub- 

 stances formed on the mammalia, on what part soever 

 of the body they may appear. No part of the body 

 in the mammalia appears to be capable of secreting 

 horny matter but the skin, and the skin does not 

 appear to be capable of secreting any other kind of 

 permanent matter. There are particular glandulous 

 pores or follicles for the secretion of this matter, and, 

 according as these are situated, so is the distribution 

 of the matter produced ; and according to their size 

 and distribution it is fur or hair, or bristles, or horny 

 appendages of some kind or other. Various circum- 

 stances affect its production in the same animal. If 

 it is transported from a cold climate to a warm one, 



the pores producing the hair or fur become abortive 

 in part, and the coat gets thinner ; and if the change 

 of climate is made the other way, the opposite results 

 are produced. The quills on the porcupines, and the 

 spines on the hedgehogs and some other animals, 

 appear to be of the nature of single hairs, each pro- 

 duced by one follicle, and not by the agglutination 

 of several into one mass, for they are not liable to 

 split longitudinally. 



The bristles of the hog, on the other hand, do 

 appear to be the production of several pores ; for, 

 though they are compactly soldered together at their 

 basal parts, they are easily split at the points, and 

 generally partially so split in a state of nature. Nails, 

 claws, and all the true horns, including that of the 

 rhinoceros among the rest, are always produced from 

 numerous pores or follicles ; and, though the sub- 

 stance of the epidermis appears to proceed toward 

 them, as we can trace by the descent of a temporary 

 hurt on the back of the thumb or finger, passing 

 along the nail as a white spot ; yet, if the follicles 

 are destroyed, they are not again produced ; or, if 

 they are injured, the production of them is deformed. 

 If a nail, horn, or a hoof, is entirely torn oft", 

 together with the roots, as we call them in ordinary 

 language, it never again grows. In nails and claws, 

 and also in hoofs, the growth appears to be constant ; 

 but in many horns it is annual, the different years 

 appearing as separate rings on the basal part of the 

 horn, which can sometimes be separated from each 

 other without much difficulty. 



The horn of the rhinoceros grows on a disc, which 

 appears to be very closely set with pores, the fibres 

 from which come into contact as soon as they issue 

 from their pores, and thus the}' are closely soldered 

 together, as is the case in all the horny appendages. 

 We cannot say that these productions of horn are 

 absolutely without life, but they have in themselves 

 very little sensibility, unless they have a near and 

 immediate connexion with the bones, and in that 

 case the sensibility appears to reside chiefly in the 

 periosteum. The horn of the rhinoceros, originating 

 as it does in the skin only, has none of this sensibility. 

 The form of the disc of skin to which it is attached, 

 and the fact of its attachment equally to all the 

 parts of that disc, give it a strength of base which no 

 other horn possesses; and its fibrous structure 

 throughout makes it secure against fracture by any 

 cross strain. The circumstance of its being placed 

 over the bones of the nose, too, completely prevents 

 any concussion of the brain, even from the most 

 violent use of it ; and its central position admits of 

 its being made use of with the whole power of the 

 animal. It is thus one of the most formidable 

 weapons of defence in the whole animal kingdom, 

 and one which can be used with the least pain or 

 injury of any kind. It may also be worn down to the 

 very stump without inconvenience to its owner ; and 

 one in the gardens of the Zoological Society of 

 London, at the Regent's Park, had the horn worn 

 down to a mere stump by habitually using it against 

 the timbers of its den. This formidable weapon is, 

 however, a defence merely, that is only to be used 

 against the enemies of the animal, or sometimes, 

 perhaps, in tearing its way through branches, and 

 other obstructions, in the tangled places which it 

 frequents ; for the rhinoceros is strictly a vegetable 

 feeder, and not furnished with any apparatus for 

 biting. 



