is 



THE CAT. 



[CHAP. n. 



Certain portions of connective tissue which connect adjacent bones 

 or cartilages become very strong, and constitute the ligaments. 

 These are flattened or rounded bands, formed of straight, parallel 

 fibres and are very dense in structure, with corpuscles elongated in 

 the direction of the fibres. 



Other fibrous structures are the membranes which closely invest 

 the bones or cartilages, which membranes are called periosteum and 

 perichondrium respectively. These are formed of intersecting fibres, 

 with blood-vessels, which latter are destined to supply the structures 

 which the membranes invest. A more delicate connective tissue 

 penetrates into the cavities of many bones, and is loaded with fat, 

 forming what is known as marrow. Fat, or " adipose tissue," con- 

 sists of round or oval vesicles (or minute bags), containing an oily 

 matter. The vesicles are mostly from the -j^tla. to the ^-oVth of an 

 inch in diameter. In the earliest period of its existence the 



a. Fibro-cartilage. 



Fig. 4. CAT'S CABTILAOE, GREATLY MAGNIFIED. 

 &. Hyaline cartilage, showing the nucleated cells enclosed in the capsules. 



skeleton consists entirely of connective tissue, but becomes largely 

 transformed into bone i.e., it ossifies by the deposition of cal- 

 careous salts around the blood-vessels, which advance and invade 

 the tissue about to ossify. 



4. CARTILAGE, is an opaque, firm but highly elastic substance, 

 generally of a bluish- white colour. Like connective tissue it consists 

 of a matrix, and this contains very distinct cells. The matrix, 

 however, is generally homogeneous. Such is hyaline cartilage. Certain 

 cartilage, however, contains fibres, and is therefore called fibro- 

 cartilage, and if it contains elastic tissue also, it is known as yellow 

 fibro -cartilage. The cells are inclosed, either singly or in groups, 

 n rounded, unbranched hollows termed capsules, the walls of which 

 may be somewhat denser than the rest of the matrix. Cartilage 



