146 PHYSIOLOGY FOR NURSES 



than in boys. Girls between twelve and fifteen are bet- 

 ter developed than boys of that age, while beyond fif- 

 teen the boy's growth is stimulated while the girl's is 

 moderated. Consequently the male overtakes and passes 

 the female. Growth, particularly of the skeleton, is 

 not arrested by underfeeding. The thymus and pitui- 

 tary glands form hormones which stimulate the growth 

 of the skeleton, which will, in the underfed, continue to 

 grow at the expense of the other tissues, notably the 

 muscles. Possibly some such internal secretion, or the 

 derangement of an internal secretion, is influential in 

 the growth of tumors, such as cancer. Whether man 

 may learn to control, by proper diet, the rate and 

 amount of growth, is still unknown; but the indications 

 are that a further knowledge of the internal secretions 

 may point out the method by which dwarfism and 

 gigantism may be avoided and a uniform growth may be 

 attained. A much larger proportion of ingested food 

 is utilized for growth in the lower animals than in man. 

 In a large number of mammals it has been determined 

 that 340 out of every thousand calories is used for 

 growth, while man employs but five per cent for the 

 same purpose. 



After growth ceases, our food is employed in creating 

 energy and effecting repair. Gradually the protoplasm 

 loses its power of growth, maturity is reached, decline 

 begins, and death finally terminates the existence of the 

 individual. With no intervening disease or injury, and 

 with perfect food and surroundings, probably the ulti- 

 mate end would be reached by the simultaneous death, 

 or wearing out, of all the tissues, and life would end 

 like the wonderful "One-Hoss Shay"- 



"All at once and nothing first, 



Just as bubbles do when they burst, ' ' 



