134 



vaneement of a science, perhaps of the first importance to man- 

 kind, he will, as soon as more pressing duties permit, commu- 

 nicate other facts, which lie lias collected respecting the deve- 

 lopment of other organs. 



A division of the skeleton, founded on physiological princi- 

 ples, would, if attainable, be much superior to any other, in 

 the consideration of the phenomena exhibited diiriug its deve- 

 lopment; but such a division is impracticable, in consequence 

 of the same part being frequently subservient to very different 

 functions. \Ve nm^t therefore follow an arrangement founded on 

 the portions of the body, into the formation of which the dif- 

 ferent parts of the skeleton enter ; and as, perhaps, none will an- 

 swer the object of this enquiry better, than the common divi- 

 sion into head, trunk, and extremities, it will be followed through- 

 out these Essays. 



I. HEAD. 



The head is composed of a great number of bones, so arranged 

 and connected together as to form an assemblage of cavities, 

 destined for the reception and defence of injportant parts; par- 

 ticularly the brain, and many of the organs of external sensa- 

 tion.* Each of these cavities may therefore form the head of 



* The organs of sensation are divisible into external and internal. The former make uo 

 acquainted with surrouuding bodies, and the latter with tlie state of our own system. 



