CHAPTER V. 



THE cat's muscles. 



§ 1. The cat performs conspicuous general bodily movements — 

 locomotive actions, such as walking, running, and jumping — and also 

 a number of movements of various portions of the body. Some of its 

 movements resemble those which are executed by ourselves at will, 

 and therefore called " voluntary motions ; " others resemble those 

 wliich we know to be in ourselves automatic, or involuntary. 



Amongst the roluntarij movements are the various movements of 

 the several members, such as the tail, the tongue, &c., together with 

 those by the aid of which the animal may change its facial expres- 

 sion, or may give audible expression to its various feelings. 



Amongst its involuntary or automatic movements are those which we 

 shall find take place in the heart, intestines, and in other viscera. 



All these motions, of whatsoever sort, are performed by muscles 

 of different kinds, shapes, and sizes. 



It is of muscles that the bulk of the cat's body — that is to say, all 

 its " flesh " — is formed. The muscular system, therefore (by investing 

 the endo-skeleton as it does), largely determines the shape of the 

 trunk and limbs, though its essential function is the production of 

 motion. 



The study of the muscles is called myology. 



The muscular system of the cat consists of masses of very different 

 sizes and shapes, arranged in most various aggregations of muscles, 

 such aggregations being separated from each other by delicate 

 sheets of connective tissue called /r^scvVr or aponeuroses. Yet more 

 delicate fibrous membranes invest every single muscle, and penetrate 

 between its component portions, conveying nerves and blood-vessels 

 to them. 



Other skeletal structures with which the muscles are directly 

 connected, are those dense bands of connective tissue ah'cady 

 referred to as " tendons." 



§ 2. Muscular substance constitutes a peculiar kind of tissue. It 

 is a motor tissue because it has the power of producing motion by 

 " contraction," that is, by an alteration in its shape which affects 

 the parts of the body to which it is attached. It has also a special 

 chemical composition. It is made up for nearly three-fourths of 



