OP THE ORGANS. 91 



constitutes the epidermis, the nails, hairs, and all the horny 

 parts of animals. Although a slight difference appears to exist 

 between the horny and epidermic matters, it is not sufficiently 

 great, to prevent us from referring them to the same sub- 

 stance. M. Meyer, who has recently given a new classifica- 

 tion of the solids of the human body, looks upon the mem- 

 brane of the tympanum, the cornea and crystalline, as being 

 formed of this substance, which he calls the scaly, or lamel- 

 lated tissue; but this approximation has no foundation, parti- 

 cularly the first. The epidermic substances are remarkable 

 for the facility and promptitude of their reproduction. 



93. The names of fibre, tissue, organ, &c., generally 

 designate the organic solids. The meaning attached to them 

 should be more particularly specified. We call tissue, every 

 part that is distinct from another by its texture. The tissue dif- 

 fers from the fibre, only inasmuch as the latter is the finer and 

 composing part of it. A tissue may be formed by fibres that 

 are similar or dissimilar. An organ, generally, results from 

 the reunion of several tissues. These distinctions however, 

 are not absolute: thus the cellular tissue represents at the same 

 time, a particular fibre, a tissue formed by that fibre and an 

 important organ of the animal economy. Generally speaking, 

 the fibre is the element, the tissue indicates the arrangement 

 of parts and the organ, a compound part which has a peculiar 

 action. Almost all the solids are formed by the cellular fibre 

 and its two modifications; some tissues have, for a base, the 

 muscular and nervous fibres ; one alone, which is the tegu- 

 mentary tissue, contains the epidermic substance. The organs 

 are, almost always, parts more or less compound; thus in a 

 muscle we find the muscular fibre, the cellular tissue which 

 surrounds it, and, at the extremity, the tendon to which it is 

 attached; in the same way in a nerve, there is a soft and me- 

 dullary substance in the centre, and externally a particular 

 membrane called the neuralima. Certain parts, such as the 

 stomach, the eye, are still more compound. Generally, every 

 organ or acting part contains cellular tissue, vessels and nerves. 

 The cellular tissue is the most extended: there is no one part 

 where it is not to be found under one form or another. After 



