Ciliary Motions in Reptiles and Warm-blooded Animals. 123 



the female genital, and in the respiratory organs of mammalia, 

 birds, and reptiles, the cilia cannot be mistaken. They are 

 most conspicuous in the oviduct of birds and serpents, less so in 

 that of mammalia, and still less in the mouth of the salamander, 

 # While the motion is swift, the cilia can be distinguished only 

 by a practised eye, but when it relaxes, they can be perceived 

 rising and falling like oars, till at last,- when all movement has 

 ceased, they stand out like stakes from the edge of the folded 

 membrane. Their figure can then be distinctly seen, tapering 

 from the base to their excessively fine and delicate point ; their 

 substance is clear, without any appearance of granular structure, 

 and their consistence is exceedingly soft and tender, so that they 

 are very easily destroyed. 



No extrinsic agency has any influence over the vibratory mo- 

 tions in the three higher classes of vertebrata. The contraction 

 of the subjacent muscular textures, as in the uterus of mammalia, 

 merely hinders the observation of the phenomenon, which be- 

 comes clearly visible on removing them. Animal heat also ex- 

 erts no special influence; the vibrations being equally brisk in 

 parts that have long been cold, or which have lain in cold water, 

 as in those which are quite warm. 



In the same animals also, the vibratory motion is not only of 

 sufficient force to propel small particles immediately adjacent to 

 the surface, but is such also, that, by its means, small portions of 

 the mucous membrane, when detached, move themselves through 

 the fluid. This last effect is striking enough, but it is not seen to 

 such a degree as we have had occasion to witness it in detached 

 portions of the mussel. Although the vibratory motion of the 

 latter is by no means of greater rapidity, force, and intensity 

 than in the vertebrata, yet it possesses far greater durability ; 

 since, according to our own experiments, it continues to exist 

 with undiminished vigour in mussels which are in a semi-putrid, 

 softened, and macerated condition. In the vertebrata, on the 

 other hand, the addition of a drop of acid or alkaline solution to 

 the fluid instantly arrests the motion.* 



* I have found that the motion on the gills of batrachian larvae continues 

 in water deprived of air by boiling, or impregnated with carbonic acid, or sa- 

 turated with muriate of morphia. In the sea mussel, it is instantaneously 

 stopped by fresh water,— W. S. 



