58 GENERAL ANATOMY OF THE TISSUES. 



Literature. — Purkinje et Valentin, 'De phsenomeno generali 

 et fundamental! motiis vibratorii continni/ Yratisl. 1835, 

 (Discovery of ciliary movement in the higher animals) ; Henle, 

 1 Symbolae ad anatom. vill. int./ Berol. 1837; 'On the distri- 

 bution of the epithelium in the human body/ Berlin, 1838; 

 and upon the development of mucns and pus, and their 

 relation to the epidermis (first exact description of the different 

 epidermic cells) ; Valentin, art. Ciliary Motion, in Wagner's 

 'Handworterbuch/ Jasche, 'De telis epithelialibus in specie et 

 de iis vasorum in genere/ Dorp. 1847. 



§ 22. 



Cartilage. — Cartilage consists of a solid, but elastic, bluish, 

 milk-white or yellowish substance, which presents two morpho- 

 logical conditions ; appearing, firstly, as a simple parenchyma 

 composed of cells; and secondly, as a cellular tissue, with an 

 intermediate substance or matrix between the elements. The 

 cartilage cells present little peculiarity in respect of form; 

 they are generally round or elongated, frequently flattened or 

 fusiform, very rarely stellate (in Cuttle-fishes and Sharks, and in 

 enchondroma) . Their membrane is ordinarily thick, frequently 

 invested by concentric lamina?; the contents are clear and more 

 fluid with a single nucleus, and, though not constantly, with one 

 or many fat globules. The interstitial substance is either 

 homogeneous or finely granulated or fibrous, even with clear 

 separable fibres. The chemical characters of cartilage are in 

 some respects but little known. It is ascertained, however, that 

 the cells and the intermediate substance are composed of 

 different substances. The membranes of the cartilage cells, in 

 fact, are not dissolved by boiling, and offer a lengthened 

 resistance to alkalies and acids, peculiarities which distinguish 

 them from the substances which yield gelatine, but approximate 

 them to elastic tissue. The contents of the cells coagulate in 

 water and dilute acids, and are readilv dissolved bv alkalies. 

 The interstitial substance is, in most cartilages, chondrin, and 

 only in the reticulated cartilages is it a substance closely 

 allied to that of the elastic tissue. Consequently the cartilages, 

 which consist only of cartilage-cells, yield no gelatine upon 

 boiling, and its occurrence is no essential character of cartilage. 

 Physiologically, the solidity and elasticity of the cartilages are 



