MATERIAL COMPOSITION OF MAN. 43 



Lastly, the possession of sensibility and locomotility leads to other 

 characteristics of animated beings. These functions are incapable of 

 constant, unremitting exertion. Sleep, therefore, becomes necessary. 

 The animal is also capable of expression, or of language, in a degree 

 proportionate to the extent of his sensibility, and of his power over the 

 beings that surround him. 



But these differences in function are not so discriminate as they may 

 appear at first. There are many animals, that are as irresistibly at- 

 tached to the soil as the vegetables themselves. Like the latter, they 

 must, of necessity, be compelled to absorb their food in the state in 

 which it is presented to them. Sensibility and locomotility appear, in 

 the zoophyte, to be no more necessary than in the vegetable. No 

 nervous, no muscular system is required; and, accordingly, none can 

 be traced in them ; whilst many of those spontaneous motions of the 

 vegetable, to which allusion has been made, have been considered by 

 some to indicate the first rudiments of sensibility and locomotility; and 

 Linnaeus 1 has regarded the closure of the flowers towards night as the 

 sleep, and the movements of vegetables, for the approximation of the 

 sexual organs, as the marriage, of plants. 



II. GENERAL PHYSIOLOGY OF MAN. 



The observations made on the differences between animals and vege- 

 tables have anticipated many topics, that would require consideration 

 under this head. These general properties, which man possesses along 

 with other animals, have been referred to in a cursory manner. They 

 will now demand a more special investigation. 



1. MATERIAL COMPOSITION OF MAN. 



The detailed study of human organization is the province of the 

 anatomist, of its intimate composition, that of the chemist. In ex- 

 plaining the functions executed by the various organs, the physiologist 

 will frequently have occasion to trench upon both. 



The bones, in the aggregate, form the skeleton. The base of the 

 skeleton is a series of vertebrse, with the skull as a capital, itself re- 

 garded as a vertebra. This base is situate on the median line through 

 the whole trunk, and contains a cavity, in which are lodged the brain 

 and spinal marrow. On each side of this, other bones, which by some 

 have been called appendices, are arranged in pairs. Upon the skeleton 

 are placed muscles, for moving the different parts of the body ; and for 

 changing its situation with regard to the soil. The body is divided 

 into trunk and limbs. The trunk, which is the principal portion, is 

 composed of three splanchnic cavities, the abdomen, thorax, and head, 

 situate one above the other. They contain the most important organs 

 of the body, those that effect the functions of sensibility, digestion, 

 respiration, circulation, &c. The head comprises the face, in which are 

 the organs of four of the senses sight, hearing, smell, and taste, 

 and the cranium, which lodges the brain the organ of the mental 

 manifestations, and the most elevated part of the nervous system. The 



1 Amcenit. Academ., torn. iv. 



