

METABOLISM. 481 



The fatigue of muscle is slowed by the use of sugar. For four 

 days Dr. F. S. Lee gave animals phloridzin, which sweeps the greater 



.part of the carbohydrate material., or .glycogen, out of the muscles. 

 Then he irritated the tibialis anticus, and, while it gave 1,000 con- 

 tractions per minute on electrical stimulation normally, after the 

 removal of glycogen by the phloridzin the, contractions were only from 



,200 to 400 per minute. These experiments proved that carbohydrates 

 assisted the muscle in its contraction. He made another series of 

 experiments upon the muscles which had their glycogen removed by 



.phloridzin, and then gave 50 grams of dextrose. Then electrical irri- 

 tations were used on the muscle, which gave 560 contractions per 

 minute. Here the glucose restored the muscle. 



Fats. 



The quantity of fat in healthy persons may vary greatly: from 

 2.5 to 23 per cent. Fats are encountered in two forms in the organism : 

 (a) as an emulsion in the nutritive fluids; (b) in drops in small 

 particular cells, or in the interior of tissue cells. While in the state 

 of emulsion the fats are in circulation; in the second state they are 

 at rest. The combustion of fats produces water and C0 2 . 



The fats can be stored by the feeding of fat. When Munk fed a 

 dog, starved for thirt} r -three days, with meat and some rape seed oil 

 daily for seventeen days, he found at the end of the time a large 

 quantity of fat, which showed a storing of fat from the oil. In this 

 fat was found erucic acid, which belongs to the rape seed oil and not 

 to normal fat. Fats can be stored from soaps and fatty acids. 



In organs continuously working we find fat, especially in the 

 heart and kidneys. There is more in the kidney than in the heart. 



Fat is also produced from the carbohydrates. Fats are used up 

 during abstinence, during insufficient diet, or during sickness. The 

 energy of fat is transformed into heat and into mechanical or chemical 

 work. Fat is a steady source of energy in work. Hence, a man who 

 works has need of more fat than one who pursues a sedentary life. 



The liver becomes loaded with fat from poisoning by phosphorus. 

 Here the fat is imported from other storage places in the body, espe- 

 cially from the subcutaneous fat of the abdomen. 



Proteid decomposition is primarily in relation with the amount of 

 proteid ingested. As the amount of proteid given increases, the 

 amount of fat burned decreases. The addition of a considerable 

 amount of fat to a proteid diet neither increases the metabolism of fats 

 nor the total metabolism. 



