392 Analogy beiwecfi Vegetables and Animals 



but in the elephant and rhinoceros it is thick, glabrous, and 

 coarse. The animal, like the vegetable, epidermis is under- 

 going a constant renewal, and when detached by injury is very 

 speedily reproduced ; indeed, its reproductive power is greater 

 than that of any other animal solid. Its use is chiefly to pro- 

 tectthe delicate structures, over which it is extended, and to 

 regulate the quantity of the cuticular exhalation. 



The rete mucosum, which is analogous to the cellular 

 integument of plants, is situated immediately under the epi- 

 dermis. It contains the colouring principle of the skin, 

 which, by its different shades, distinguishes mankind into 

 five principal varieties. It is likewise the cause of the differ- 

 ence of colour in different parts of the body of the same person. 

 In the European it is of a light hue, in the Asiatic it is olive ; 

 in the aboriginal American it is red j in the Malay it is tawny ; 

 and in the negro, in whom it exists in the greatest quantity, it 

 is black. 



The cutis, or true skin, is composed of a number of small 

 fibres, or plates, closely interwoven together; and has at- 

 tached to it a vast quantity of nerves, blood-vessels, and 

 absorbents, which are minutely ramified over every part of it. 

 The blood-vessels form innumerable plexuses, and give it a 

 reticulated appearance. The external surface of the cutis is 

 compact, while the internal is loose and irregular. Bark, it 

 may be observed, is a very slow conductor of heat; so that 

 the more internal parts of plants easily preserve their warmth 

 during winter, and during summer receive no injurious effects 

 from the high temperature of the surrounding atmosphere. 

 The cutaneous laminae of animals, especially the epidermis 

 and rete mucosum, are, like the bark of vegetables, media 

 through which heat is transmitted with great difficulty. 

 Hence the parts adjacent to the skin are prevented from suffer- 

 ing by the extremes of temperature to which the body is so 

 constantly exposed. From this account it will be perceived, 

 that the cutaneous tissue of vegetables possesses so exact a 

 similitude to that of animals, that a description of either 

 will answer to both. 



The surface of plants is often destitute of covering ; but 

 generally it is clothed either with down, hair, or wool, all 

 of which are productions or modifications of the epidermis. 

 The hair is of various descriptions, being sometimes long 

 and flexible, at others short and bristly. The woolliness, 

 too, differs considerably in its character. In some cases 

 it is extremely delicate and easily detached, as on the leaves 

 of the coltsfoot ; in other instances it is of a coarser texture, 

 as on the skin of the peach. Sometimes, as in the Poten- 



