THE BONES 251 



b. 1504 : 61-70. The Cell the Foundation of Life. 



c. 1505 : 10-16. Protozoa (One-celled Animals). 



d. 1507 : 17-24. Structure, Life, and Work of Cells. 



e. 1509 : 1-9. Plant and Animal Life in the Simplest 



Forms. 



/. 1510 : 9. Meaning and Importance of the Cell. 



g. 1511 : 5-6. Cell Structure. 



h. 1512:301. The Cell. 



i. 1704 : 281-286. Physiological Chemistry. 

 j. 1708 : 409-411. Chemistry of Life. 



185. THE BONES, OR FRAMEWORK 



Just as in plants the stems serve to hold up the body, so in 

 animals some stiff structure is necessary. The complete 

 framework is called the skeleton, and its parts are called 

 bones. Bones are hollow in order to obtain the greatest 

 strength with the least amount of material, and the cavity 

 is used to supply the bones with nourishment. 



Most animals have their framework covered with flesh, but 

 some have a stiff outside covering which serves the same 

 purpose as the skeleton, and acts as a protection against 

 enemies. See Section 181, The Invertebrates. 



In order to allow free movements, the bones, or coverings, 

 are jointed, being held together by cartilage. These places 

 of bending, or yielding, are called joints. 

 References : 



1. 1501:357-363. The Bones. 



2. 1501 : 364-369. The Joints. 



3. 1503 : 371-379. Bones and Joints. 

 a. 1505:29-38. The Skeleton. 



6. 1506 : 191-202. Osseous System of Bones. 



c. 1509:10-25. The Skeleton. 



d. 1510:103-111. The Skeleton and the Muscles. 



e. 1511 : 11-43. The Osseous System, or Skeleton. 



