sect. 24.] CARTILAGE-TISSUE. 47 



In form, the cartilage-cells present but little that is peculiar; 

 they are mostly round or oblong, frequently flattened or fusiform, 

 very rarely stellate (in Cephalopoda, Rays ; in Enchondromatous 

 growths). Their membrane is delicate at first; but subsequently 

 becomes, in most places, covered on its outer side with a second 

 layer, which bears the same relation to it as the cellulose-mem- 

 brane of vegetable-cells does to the primordial utricle. Accord- 

 ingly, there arc two parts to be distinguished in cartilage-cells : 

 1. The proper cell, or the primordial utricle (the cartilage-corpus- 

 cle of authors), an extremely delicate-walled cell, filled with con- 

 tents sometimes clear and fluid, sometimes dark and firm, together 

 with a nucleus; and, 2. The external secondary membrane, or the 

 cartilage-capsule (the cartilage-lacuna of authors), a firm, clear, or 

 yellowish layer, formed by an excretion of the primordial utricle, 

 and closely surrounding the inner cell. By continued excretion 

 from the latter, deposited upon its inner surface, the outer cell- 

 wall may attain a laminated appearance, and a very considerable 

 thickness. The contents of the delicate cartilage-cell coagulate 

 and shrink up on the addition of many re-agents, and even of 

 water; so that an interval is formed between it and its capsule 

 (fig. 14 — 1,2), and it becomes converted into a dark and jagged 

 corpuscle, without any distinct nucleus, the nature of which it is 

 diflicult to recognise. 



In the cartilage-cells we find, very frequently, a multiplication 

 of cells, which process is effected by division of the primordial 

 utricle within the cartilage-capsule. Around 

 the secondary cells there are then formed 

 new cartilage-capsules; whilst the capsules 

 of the mother-cells gradually blend with the 



intermediate substance, which accordingly 



owes its origin, in part at least, to the cells. 



The matrix is either homogeneous, finely 



granular, or fibrous, even with distinct and 



separable fibres. The chemical characters of Three ]uiman cartaage _ cel i S) 



cartilage-tissue are as yet but little known. ™^t£? £S* 4£S 



This much is certain, that the cells and the ^\S wh £ & P S 



matrix do not consist of the same materials; ££S H 5§*^'S5gJ "»" 



that is to say, the membranes of the proper &J3 Ib SBMM& 



cartilage-cells do not dissolve on boiling, and &MtSS&Jr2. SS 



long resist the action of alkalies and acids — *&**  "■ Cartuage-capside. 



» b. Primordial utricle, with tlie 



properties which distinguish them from the eeiicontents and nucleus, which 



r l o in 2 is concealed. 



gelatiniferous substances, but approximate 



