CILIARY MOTION. 



579 



' Ciliary motion seems to be alike independent of the will, 

 of the direct influence of the nervous sj'stem, and of muscular 

 contraction, for it is involuntary ; there is no nervous or 

 muscular tissue in the immediate neighbourhood of the 

 cilia, and it continues for several hours after death or 

 removal from the body, provided the portion of tissue 

 under examination be kept moist. Its independence of 

 the nervous system is shown also in its occurrence in the 



153- ! 



Fig. 154. t 



lowest invertebrate animals apparently unprovided with 

 anything analogous to a nervous system, in its persistence 

 in animals killed by prussic acid, by narcotic or other 

 poisons, and after the direct application- of narcotics to 

 the ciliary surface, or the discharge of a Leyden jar, or 

 of a galvanic shock through it. The vapour of chloroform 

 arrests the motion ; but it is renewed on the discon- 

 tinuance of the application (Lister). According to Kuhne, 

 the movement ceases in an atmosphere deprived of oxygen, 

 but is revived on the admission of this gas. Carbonic 

 acid stops the movement. The contact of various substances 

 will stop the motion altogether ; but this seems to depend 

 chiefly on destruction of the delicate substance of which 

 the cilia are composed. 



Little or nothing is known with certainty regarding 

 the nature of ciliary action. As Dr. Sharpey observes, 



* Fig. 153. Spheroidal ciliated cells from the mouth of the frog ; 

 magnified 300 diameters (Sharpey). 



t Fig. 154. Columnar ciliated epithelium cells from the human 

 siasal membrane ; magnified 300 diameters (Sharpey). 



p p 2 



\\ 



