* DEFINITIONS. SECT. II. i. 



2. The longitudinal mufcular fibres compofe the 

 locomotive mufcles, whofe contractions move the 

 bones of the limbs and trunk, to which their extre- 

 mities are attached. The annular or fpiral mufcular 

 fibres compofe the vafcular mufcles, which confti- 

 tute the inteflinal canal, the arteries, veins, glands, 

 and abforbent veffels. 



3. The immediate organs of fenfe, as the retina 

 of the eye, probably con fifl of moving fibrils, with 

 a power of contraction lirnilar to that of the larger 

 mufcles above defcribed. 



4. Tiie cellular membrane confifts of cells, which 

 refemble thofe of a fponge, communicating with 

 each other, and connecting together all the other 

 parts of the body. 



5. The arterial fyfte'tn confifts of the aortal and 

 the pulmonary artery, which are attended through 

 their whole courfe with their correfpondent veins. 

 The pulmonary artery receives the blood from the 

 right chamber of the heart, and carries it to the mi- 

 nute extenfive ramifications of the lungs, where it 

 is expofed to the action of the air on a furface equal 

 to that of the whole external fkin, through the thin 

 itioift coats of thofe veffels, which are fpread on the 

 air-cells, which conftitute the minute terminal ra- 

 mificatitihs of the wind pipe. Here the blood 

 changes its colour from a dark red to a bright fear- 

 let. 'It is then collected by the branches of the pul- 

 monary vein, and conveyed to the left chamber of 

 the heart. 



6. The aorta is another large artery, which re- 

 ceives the'blood from the left chamber of the heart, 

 after it has been thus aerated in the lungs, and con- 

 veys it by afcending and defcending branches to 

 every other part of the fyftem ; the extremities of 

 this artery terminate either in glands, as the falivary 

 glands, lacrymal glands, &c. or in capillary veflels, 

 which are probably lefs involuted glands \ in thefe 



fome 



