PASSIVE OK&ANS OF LOCOMOTION. 479 



in vivisections ; but Longet has further shown 'that dogs 

 with an opening into the trachea are frequently able to run 

 and leap with " astonishing agility." He also saw a horse, 

 with a large canula in the trachea, that performed severe 

 labor and drew heavily-loaded wagons in the streets of 

 Paris. 1 



Passive Organs of Locomotion. 



It would be out of place to describe fully and in detail 

 all of the varied and complex movements produced by mus- 

 cular action. Many of these, such as the movements of deg- 

 lutition and of respiration, are necessarily considered in con- 

 nection with the functions of which they form a part ; but 

 others are purely anatomical questions. Associated and an- 

 tagonistic movements, automatic and reflex movements, etc., 

 belong to the history of the motor nerves, and will be fully 

 considered under the head of the nervous system. 



The study of locomotion involves a knowledge of the 

 physiological anatomy of certain passive organs, the bones, 

 cartilages, and ligaments. Though a complete history of the 

 structure of these parts trenches somewhat upon the domain 

 of anatomy, we are tempted to give a brief description of 

 their histology, as it will complete our account of the tissues 

 of the body, with the exception of the nervous system and 

 the organs of generation, which will be taken up hereafter. 



Locomotion is effected by the muscles acting upon cer- 

 tain passive, movable parts. These are the bones, cartilages, 

 ligaments, aponeuroses, and tendons. We have already de- 

 scribed the fibrous structures, and it only remains for us to 

 study the bones and cartilages. 



Physiological Anatomy of the Bones. The number, clas- 

 sification, and relations of the bones are questions belonging 

 to descriptive anatomy ; and the only points we propose to 

 consider refer to their general or microscopic structure. 



1 LONGET, Traite de physiologic, Paris, 1869, tome ii., p. 669. 



