3o2 CONCLUSION. 
explain ** in what manner the animal effected 
those modifications of the tube and its contained 
air, on which the variation of its buoyancy 
depended."* The theory which supposes the 
chambers of the shell to be permaneiitlij Jilled with 
air alorie^ and the siphuncle to be the organ which 
regulates the rising or sinking of the animal, by 
changing the place of the pericardial fluid, seems 
adequate to satisfy every hydraulic condition of 
a Problem that has hitherto received no satis- 
factory solution. 
I have dwelt thus long upon this subject, on 
account of its importance, in explaining the 
complex structure, and hitherto imperfectly un- 
derstood functions, of all the numerous and widely 
disseminated families of fossil chambered shells, 
that possessed siphunculi.t If, in all these fa- 
milies, it can be shewn that the same principles 
of mechanism, under various modifications, have 
prevailed from the first commencement of or- 
ganic life unto the present hour, we can hardly 
avoid the conclusion which would refer such 
unity of organizations to the will and agency 
of one and the same intelligent First Cause, and 
lead us to regard them all as *' emanations of 
that Infinite Wisdom, that appears in the shape 
and structure of all other created beings." J 
* The recent observations of Mr. Owen shew, that there is no 
gland connected with the siphuncle, similar to that which is 
supposed to secrete air in the air-bladder of fishes. 
t See Sup. Note. 
\ Dr. Hook's Experiments, p. 306. 
