PASSIVE ORGANS OF LOCOMOTION. 



549 



rounded and quite large. The cells contain generally a certain amount of fatty matter. 

 The appearance of the ordinary articular cartilage is represented in Fig. 168. 



The ordinary cartilages have neither blood-vessels, lymphatics, nor nerves, and are 

 nourished exclusively by imbibition from the surrounding parts. Their function has 

 already been sufficiently considered in treating of the synovial membranes. In the devel- 

 opment of the body, the anatomy of the cartilaginous tissue possesses peculiar interest, 

 from the fact that the deposition of cartilage precedes the formation of bone ; but we 

 have here only to do with the permanent cartilages. 



Fibro- Cartilage. This variety of cartilage presents certain important peculiarities 

 in the structure of its fundamental substance. It exists in the synchondroses, the car- 

 tilages of the ear, of the Eustachian tubes, the interarticular disks, the intervertebral 

 cartilages, the cartilages of Santorini and of Wrisberg, and the epiglottis. Its structure 

 has been very closely and successfully studied by Sappey, who has arrived at results dif- 

 fering considerably from those obtained by other observers. 



According to Sappey, fibro-cartilage is composed of true fibrous tissue, with a great 

 predominance of elastic fibres, fusiform, nucleated fibres, a certain number of adipose 



I ( 



FIG. 169. Section of the cartilage of the ear of the human subject* (Rollett.) 

 a, fibro-cartUage ; &, connective tissue. In this preparation, the cartilage had been boiled and dried. 



vesicles, cartilage-cells, and numerous blood-vessels and nerves. The presence of cartilage- 

 cells assimilates this tissue to the ordinary cartilage, although its structure is very much 

 more complex. The fibrous elements above mentioned take the place of the homogeneous 

 fundamental substance of the true cartilage. The most important peculiarity in the 

 structure of this tissue is that it is abundantly supplied with blood-vessels and nerves. 



The reader is referred to works upon anatomy for a history of the action of the muscles. 

 In some works upon physiology, will be found descriptions of the acts of walking, running, 

 leaping, swimming, etc. ; but we have thought it better to omit these subjects, rather than 

 to enter as minutely as would be necessary into anatomical details and to give elaborate 

 descriptions of movements which are simple and familiar. 



Voice and Speech. 



There are few subjects connected with human physiology of greater interest than the 

 mechanism of voice and speech. In common with most of the higher classes of animals, 

 man is endowed with voice ; but, in addition, he is able to express by speech the ideas 

 that are the result of the working of the brain. In this regard there is a difference be- 

 tween man and all other animals. It is the remarkable development and the peculiar 



