90 INTRODUCTION. 



Finally, the cartilaginous and bony systems belong to the 

 cellular tissue, and owe their solidity to its condensation and 

 the great quantity of earthy salts that.substance contains. 



A second order of organs is formed, essentially, by the 

 muscular fibre: this is, the muscles, whether belonging to the 

 bones, to the external and internal teguments, to the senses, 

 or to the heart. 



The nerves and the central nervous masses, constitute the 

 third and last order of organs, essentially formed by the nerv- 

 ous substance. 



It will be seen that this classification reposes on the basis 

 indicated by Haller, and which truly exist in nature. 



91. The order in which the genera of organs should be 

 arranged, may be founded on various bases: if we paid any 

 attention to the universality, more or less great, of the organs 

 in the series of animals, the cellular tissue should be placed 

 first; after it would come, the tegumentary organs; then the 

 muscles and nerves, the vessels, the glands ; the cartilaginous 

 and bony, the ligamentous and serous tissues would be placed 

 last as peculiar to the vertebrata. Another order would be 

 followed if we were first to class the kinds of organs that be- 

 long to the common or vegetative functions, and next, those 

 which form the apparatus of functions proper to animals. 

 Another order would be established, if, like Bichat we were 

 first to arrange the general systems, as the cellular tissue, the 

 vessels and the nervesj and then the particular systems. It is 

 a matter of but little importance, although it is preferable to 

 arrange the organs from their analogies, as we have done. 



92. Several physiologists, still place the epidermic, or 

 horny substance, among the primitive fibres; but this almost 

 inorganic substance, produced by excretion can not be consi- 

 dered as an anatomical element. The characters assigned to 

 it are the following; it contains no distinct cellulosity; ma- 

 ceration reduces it into a sort of mucilage; chemistry proves 

 that it contains albumen, according to some, and mucus accord- 

 ing to others, not very different things, since mucus appears 

 to be albumen united to soda. This substance is that which 



