SOLID PARTS. 57 



at others, placed within the articulations to act as elastic cushions ; and, 

 in the foetus, forming a substitute for bone. Hence, cartilages are di- 

 vided into articular or incrusting, cartilages of prolongation, interarti- 

 cular cartilages, and cartilages of ossification. 



3. Muscles constitute the flesh of animals. They consist of fasci- 

 culi of red and contractile fibres, extending generally from one bone to 

 another ; and are the agents of all movements. 



4. Ligaments are tough; difficult to tear; and, under the form of 

 cords or membranes, serve to connect different parts with each other, 

 particularly bones and muscles ; hence their division, by some anato- 

 mists, into ligaments of bones as the ligaments of the joints; and 

 ligaments of muscles, as the tendons and aponeuroses. 



5. Vessels are solids, having the form of canals, in which the fluids 

 circulate. They are called according to the fluid they convey san- 

 guineous (arterial and venous), cliyliferous, lymphatic, &c. 



6. Nerves are cords, consisting of numerous tubular fasciculi. These 

 are connected with the brain, spinal marrow, or great sympathetic. 

 They are the organs by which impressions are conveyed to the nervous 

 centres, and by w T hich each part is endowed with vitality. There are 

 three great divisions of the nerves, the cerebro- spinal, true spinal, 

 and organic. 



7. Ganglions are solid knots in the course of a nerve which seem to 

 be formed of an inextricable interlacing of nervous filaments. The 

 term is likewise applied, by many modern anatomists, to similar inter- 

 lacings of the ramifications of lymphatic vessels. G-anglions may, 

 consequently, either be nervous or vascular ; and the latter, again, may 

 be divided into cJiyliferous or lymphatic, according to the kind of ves- 

 sel on which they appear. Chaussier, a distinguished anatomist and 

 physiologist, has given the name glandiform ganglions to certain organs 

 whose nature and functions are unknown, but which appear to be con- 

 cerned in lymphosis, as the thymus gland, the thyroid gland, &c. 



8. Follicles or crypts are secretory organs, shaped when simple like 

 membranous ampullae or vesicles, formed by an inversion of the outer 

 membranes of the body the skin and mucous surfaces and secreting 

 a fluid intended to lubricate them. They are often divided into the 

 simple or isolated; the conglomerate; and the compound, according 

 to their size, or the manner in which they are grouped and united to- 

 gether. 



9. Glands are secretory organs not differing essentially from the last. 

 Their organization is more complex ; and the fluid, after secretion, is 

 poured out by means of one or more excretory ducts. 



10. Membrane. This is one of the most extensive and important of 

 the substances formed by the areolar tissue. It is spread out in the 

 shape of a web; and, in man, serves to line cavities and reservoirs; and 

 to form, support, and envelope organs. 



Bichat divides membranes into two kinds, simple and compound, ac- 

 cording as they are formed of one or more layers. 



Simple membranes are of three kinds, serous, mucous, and fibrous. 



1st. Serous membranes constitute all the sacs or shut cavities of the 

 body, those of the chest and abdomen, for example. 



