ANIMAL MOTION. 431 



CHAPTER XXV. 



OF ANIMAL MOTION. 



Ciliary and Muscular Motion. Description of Cilia and ike Manner of Action. 



Muscular Fibre : its Forms, Non-striated and Striated. Muscle Juice. Manner of Contraction 

 of a Muscle : its supply of Blood-vessels and Nerves. Its Chemical Change during Activity. 

 Its Rise of Temperature. Effect of Electrical Currents. Duration of Contractility. 



Doctrine that Muscle Contraction is the result of Muscle Disintegration. Manner in which ordi- 

 nary Cohesion is brought into play. Manner of Restoration. Removal of the Heat and Oxi- 

 dized Bodies. 



Rigor Mortis. Connection of Muscle for Locomotion. Of Standing. Walking. Running. 



IT was formerly held that animals are distinguished from plants by 

 the possession of the power of locomotion, a doctrine which . 



r J J T A i -u Animal motion. 



can now no longer be regarded as true. It was also be- 

 lieved that the muscular movements of animals are due to the influence 

 of the nerves, and that a muscular fibre contracts only when stimulated 

 to do so by a nerve. This makes the possession of a nervous system 

 essential to the motions of animals. These doctrines also are erroneous. 

 Animal motion is of two different kinds : 1st. It is accomplished by 

 vibrating cilia ; 2d. By the contraction of cells arranged in the form of a 

 fibre. 



OP CILIARY MOTION. . 



The epithelial cells of the cylindrical and of the tesselated kind are 

 occasionally arranged with delicate projecting strige on their Description of 

 free extremities. The length of these varies from the - 6 -J-Q cilia and their 

 to the XQOQQ of an inch. These stria? are termed cilia, and 

 the cells are said to be ciliated. Examples are presented by the mucous 

 Fig. 208 membrane of the respiratory surface and of the nasal 



cavities ; an illustration is given in Fig. 208. The 

 cilia may be regarded as prolongations of the cell wall 

 itself. They exhibit a vibrating motion back and 

 forth, which recalls the movements of stalks of grain 

 in a field as the wind is passing over it, the ears bend- 



Ciliated cells. , , . . . r . , , 



ing down and rising again in the breeze, and throwing 

 the whole surface into waves. The cilia also exhibit a movement like 

 that known as the feathering of an oar, or sometimes as turning round 

 upon the point of attachment, as upon a centre, giving rise to a sort of 

 conical motion, the free end describing a circle. These motions seem to 



