2 CILIARY MOTION. 



trace of cilia has yet been found in any part of the urinary apparatus 

 of Mammalia. 



M. Rossignol* finds that the ciliary epithelium along the mucous lining 

 of the respiratory passages, ceases at the vesicular structure of the lung, 

 its place in the vesicles themselves being occupied by simple pavement 

 epithelium, composed of roundish or oval cells. The cessation of the 

 ciliary epithelium at the commencement of the cellular structure of the 

 lung, has been observed also by Mr. Rainey, | who states, however, that 

 the intercellular passages and the air- vesicles in which the ultimate branches 

 of the bronchial tubes terminate, are destitute of epithelium of any kind. 



Ecker J has discovered ciliary epithelium in the semi-circular canals of 

 the internal ear of Petromyzon marinus (sea lamprey). The cells were of 

 different forms, oval, roundish, flask-shaped, and angular, with nuclei and 

 granular contents. None of the cells possessed more than one cilium. 

 The movements of the cilia were principally of a lashing, fanning kind. 

 This is the first example of a ciliary structure being found in any other part 

 of the auditory apparatus of a vertebrate animal, than the Eustachian tube. 



Of the phenomena of ciliary motion. An interesting observation in 

 regard to the mode of action of the cilia, has been made by Mr. Quekett 

 in the case of the gill rays of the mussel, which explains more completely 

 than could otherwise be done, the power possessed by the cilia of propel- 

 ling fluid or solid particles in any determinate direction. He observed, 

 that besides their ordinary lashing movements, each cilium possesses a 

 kind of rotatory motion on itself, by which it turns on its own axis, through 

 the space of about a quarter of a circle, with a movement very similar to 

 that performed during the feathering of an oar in rowing. 



Nature of the ciliary motion. From experiments made on the epithelial 

 cells of the nasal mucous membrane of man, E. H. Weber)) has shewn 

 that the vibratile movements of their cilia are diminished almost to one- 

 half their usual rate by cold, and are sensibly increased by heat. In this 

 as well as in their rhythmic action and its persistence after death, the 

 ciliary movements bear a close analogy to those of the heart. The 

 influence of heat and cold is less manifest on the movements of the cilia, 

 and also on those of the heart, in cold than in warm-blooded animals. 



OF THE MUSCULAR AND THE ALLIED MOTIONS.^ 

 Of the elastic and contractile tissue of arteries. 



THE statement made by Professor Miiller,** that the middle coat 

 of arteries does not possess any muscular contractility, requires to be 



* Recherches sur la Struct, du Poumon. Bruxelles, p. 66 8. 



t Medico-Chirurg. Transact, vol. xxviii. $ M'uller's Archiv. 1844, p. 520. 



$ Medical Gazette, May 3, 1844. || Archiv. d'Anat. Gen.etde Physiol. Jan. 1846. 



U Chapter iii. p. 867, Miiller's Physiology. ** Physiology, p. 875. 



