THE ORGANIZATION OF MAN. 9 



eludes certain prolongations or appendages which serve 

 as the framework of the limbs. These limbs, four in 

 number, two upper and two lower, are suspended from 

 the trunk by the aid of what we may call bony belts, of 

 which the upper one helps to form the shoulders, while 

 the lower one forms the floor of the abdominal cavity, 

 and is called the pelvis, which means basin. 



The various organs that have been mentioned, heart, 

 lungs, stomach, intestines, liver, muscles, bones, etc., all 

 co-operate for the same purpose, the maintenance of 

 life and the growth of the body. But the parts that they 

 take are very different. Some, like the lungs, are speci- 

 ally adapted to establish between the blood and the air 

 a contact that is absolutely necessary for the life of 

 the blood. The stomach, intestines, and other digestive 

 organs transform the food into substances capable of 

 becoming part of the blood. They are organs of nutri- 

 tion or vegetative life. Other organs, such as the brain, 

 the spinal marrow, the organs of sense, and the muscles, 

 help to establish an understanding between the body and 

 the outside world : they are organs of relation. Gener- 

 ally several organs assist in the same work, and such are 

 then grouped together and constitute an apparatus. 

 Thus, the digestive apparatus includes the stomach, the 

 intestines, the liver, etc., and each apparatus can be sub- 

 divided into smaller groups of organs, each of which 

 performs a particular portion of the work to be done. 



If this examination of the organization is pursued still 

 more minutely, the organs are found to be far from sim- 

 ple : the various tissues that constitute the organs are 

 composed of simpler parts or elements, and these ele- 

 ments are all derived from a fundamental element that 

 is called a cell. 



