384 DETAILED SYNTHESIS. 



gradually acquired habits the channels for the Blood 

 must be enlarged and an EQUABLE FLOW of it thus secured. 



1234. Remark. IT is OF ESPECIAL IMPORTANCE is CASE OF THE 

 GANGLIA OF INTELLECTION, that by frequent and regular use during the 

 long period of growth, the paths of the Blood should be amplified, and 

 the ganglia acquire an aptitude for the rapid action necessary in mathe- 

 matical studies, for the more deliberate uses to which they must be ap- 

 plied in the study of the languages, and for the observational methods 

 of the natural sciences. 



SECTION VH. 



Respiration : Respiratory Apparatus. 



1235. THE ORGANS CONJOINED IN RESPIRATION par- 

 take of a threefold character; 1st, those that circulate 

 Blood; 2d, those that receive the air; 3d, those that 

 cause the air to pass into and out of its receptacles. 



1236. Those that circulate Blood THROUGH THE 

 LUNGS consist of a Heart, Arteries, Capillaries, and 

 Veins ; the three latter are parts of the lungs. 



1237. THE LUNGS ARE ALSO COMPOSED of air pas- 

 sages, elastic tissue, and enclosing membrane (Pleura). 



1238. Remark. Though the LUNGS ARE USUALLY SPOKEN OP and 

 considered as receptacles of air, they are equally such of the Blood, and 

 the quantity of it that passes through the lungs is even more startling 

 than is the amount of air breathed. More than a barrel of Blood per 

 hour, night and day, is driven through the lungs ; and if there is a fail- 

 ure of fresh air to act upon it for the brief space of a minute, it becomes 

 so much loaded with poisonous carbonic acid that consciousness begins 

 to waver, and in another minute is gone. 



1239. THE MEANS CAUSING THE AIR TO PASS INTO 

 THE LUNGS are the walls of the trunk, the contrary ac- 

 tion of which, with the elasticity of the lungs, CAUSES 

 THE AIR TO PASS OUT OF THEM. 



1240. THE ELASTICITY OF THE CARTILAGES OF THE 

 TRUNK, both of the ribs and of the spinal column, assist 



1234. What is ? 1285. What said of ? 1286. What circulate Blood ? 

 1287. How ? 1288. How ? 1289. What said of ? 1240. What said of ? 



