242 
LIFE, IN ITS INTERMEDIATE FORMS. 
Like all organic functions, the action of these cilia is 
not under the will of the animal. If, during life, a small 
portion of the gills be cut off, the motion of the cilia will 
convey the fragment swiftly away, with a smooth easy mo- 
tion, through the surrounding fluid, in a definite direction. 
It does not even cease with the life of the animal. A 
specimen which wo examined had been dead at least 
fifteen bom's, yet when we placed the torn fragments of 
the branchial, one after another, beneath the microscope, 
the energy of the ciliary action, as the wave flowed with 
uniform regularity up one side and down the other of 
every filament, filled us with astonishment. Even the 
next morning, twenty-six hours after death, when the 
tissues of the filaments were partially dissolved, the ciliary 
motion was still going on, on portions that preserved their 
integrity. 
The leaves which form the mantle are useful, not only 
for protecting these gills and the other delicate organs 
which are situated within their embrace, but for manu- 
facturing the valves of the shell. This process has been 
ably described by Professor Bymer J ones, as it takes place 
in the Scallop ( Pecten maximus), and we shall quote his 
-words : — 
“ It is the circumference or thickened margin of the 
mantle alone which provides for the increase of the shell 
in superficial extent. On examining this part, it is found 
to be of a glandular character, and, moreover, not 
unfrequontly provided with a delicate and highly sen- 
sitive fringe of minute tentacula. Considered more 
attentively, it is seen to contain in its substance patches 
of different colours, corresponding both in tint and rela- 
