94 MR. GARNER ON THE ANATOMY OF THE 
Cilia. 
The vibration which has been noticed by authors on the surface of the intestine of 
molluscous animals, originates from the passage of that canal being through the secret - 
ing sacs, into which water is drawn by the action of cilia upon their surfaces. From 
noticing the appearance on the intestine of the Chiton, I was led to find the two orifices 
described above, by which the water is drawn in. 
The beautiful and wonderful phenomenon of the vibration of the minute cilia of 
the lower animals was noticed by many of the older naturalists, but from the defect 
of their instruments, was often confounded with the circulation. Raspail has shown 
that many of the animalcules of Miiller and Baer are merely the vibratile parts of 
other animals. Home explains the rotation noticed in the embryo of the ovum of the 
Lamellibranchiata to be caused by a species of Vibrio getting into its interior and feed- 
ing upon it; and the figures which he has given of this supposed animalcule are those 
of the branchial processes of the Anodonta. The hydroferous vessels of the Radiata 
are internally covered with cilia, and it is by these that the circulation in the Beroé is 
plainly caused. I do not find them in the Crustacea nor in the Cirrhopoda, nor in the 
aquatic larve of insects. Dr. Sharpey was unable to see them in the Twnicata, but he 
might have done so with the aid of a more powerful lens. They cover in great num- 
bers the meshes of the branchie, but are unusually small in those organs. I do not 
find them on the branchie of the Cephalopoda. They are present in the stomach of the 
Asterias and Actinia, and the long white threads sometimes seen hanging from the Act. 
diantha are covered with them. 
The piercing of rocks, stones, wood, &c. by Lamellibranchiate animals cannot in every 
case take place by the mechanical action of the valves. The valves of some genera, as 
the Lithodomus amongst many others, are not at all adapted for such an action. Neither 
can such perforation be caused by a solvent fluid secreted by the animal ; for what fluid 
would dissolve so many substances, and yet not injure the animal’s own shell? The 
fact appears to be, that the phenomenon is caused by the vibratile action of the parts 
exciting constant currents of water against the substances, aided by its impetus when 
drawn in down the elongated body of the animal, and in some cases, perhaps, by the 
rasping of the valves. Often the shell, from its flattened form, or from its fitting 
closely, cannot act at all. The Patella when sticking to a rock often forms a hole an 
inch in depth, and this by the action of its ciliated branche ; the hole cannot be made 
by the shell, as it fits exactly in it, and is of such a figure that no rotation can take 
place. The Hipponyx, another Gasteropod, forms cavities in the Patella and other 
shells to which it adheres. The crypts of the Sazicava are not circular; hence M. de 
Bellevue and Osler in this instance believe them to be formed by the action of the 
phosphoric acid secreted by the animal, and they suppose this animal to inhabit rocks 
only which are composed of carbonate of lime ; which last supposition is not, to my own 
