Nutrition Studies. 71 



A healthy growing person with poor muscular development may 

 by suitable food and exercise materially strengthen and increase 

 the size of his muscles thru the thickening of the individual fibers. 

 Caspari/ studying working dogs, and Bornstein,- experimenting 

 with himself, found that when a considerable amount of muscular 

 work was performed, if the body was supplied with an abundance 

 of protein-rich food there was a small but continued gain of body 

 protein. An animal whose muscles have wasted away thru lack of 

 food or thru sickness will repair its tissues upon a return to favor- 

 able conditions, thereby storing protein. The storage of fat in the 

 body is necessarily accompanied by a very slight increase of body 

 protein, due to the growth of the tissues holding the fatty matter. 

 The framework of bone, partly of protein but largely of mineral 

 matter, is in general subject to the laws that govern the formation 

 of protein tissues. Differing from protein, the water and especially 

 the fatty matter of the body may vary greatly in total and relative 

 amounts according to heredity, the abundance and character of the 

 food, exercise, etc. 



95. The growing animal. — The body of the young, growing ani- 

 mal undergoes a rapid increase in protein tissues and bone, but 

 that of the mature animal is normally in equilibrium, i. e. the pro- 

 tein outgo equals the protein intake, there being neither increase 

 nor loss of protein tissue. Equilibrium is not possible with young 

 animals. Waters of the Missouri Station,^ experimenting with 

 yearling steers, has shown that young animals fed scanty rations 

 increase in height, even tho losing in weight. With insufficient 

 food some of the organs or parts may continue to grow at the ex- 

 pense of others, a process which, if long continued, results in injury 

 or death. An abundant supply of protein is essential for the for- 

 mation of the protein tissues of the body, and mineral matter is 

 necessary for the framework of bone. 



The suckling utilizes its food most economically. At the Wis- 

 consin Station, lambs fed cow's milk gained 1 lb. in weight for each 

 0.75 lb. of dry matter consumed. In respiration studies with a calf 

 2 to 3 weeks old, Soxhlet* found a storage in the body of 72.6 per 

 ct. of the protein, 96.6 per ct. of the lime, and 72.6 per ct. of the 

 phosphorus fed in the milk, showing that the young animal stores a 

 large portion of the digested food nutrients, including protein. As 



^ Arcbiv. Physiol., 83, 1901, p, 535. 



' Ibid., p. 548. 



^ Proc. Soc. Prom. Agr. Sci, 1908. 



*Ber. landw. chem. Vers, Stat. Wien, 1878, p. 101. 



