56 



Dr. Parkes on the Elimination of Nitrogen. [J une 20^ 



muscles whose state we can alter. We cannot alter the action of the 

 muscles of respiration, of the heart, the stomach, and intestines, &c. 

 "We cannot even reduce the voluntary muscles to a state of complete and 

 prolonged rest. There must be some movement, consequently we must 

 not expect to find large variations in the elimination of nitrogen when 

 a certain number of muscles only are kept in a state of comparative rest 

 or exercise. 



The food passing into the body after due preparation in the stomach, 

 liver, and lungs, forms in the blood a reservoir or store of nutriment 

 from which the different parts of the body take their supply as they 

 require it, or according as the special stimulus of each enables it to ap- 

 propriate it. 



In these two men 19" 6 grammes, or 302 grains passed daily into, and 

 then out of, the store into the various nitrogenous tissues. This quantity 

 exactly sufficed in the then state of activity of all the organs to preserve 

 perfect action, and to keep the body-weight constant. 



A certain number of muscles being brought into a state of rest, the 

 nitrogenous elimination increased ; in other words, the muscles appro- 

 ])riated nitrogen in less, and gave it off in greater, amount, owing, if my 

 explanation be correct, to their more rapid disintegration during rest 

 than exercise. This may be understood by supposing that if in the 

 twenty-four hours the voluntary muscles are in a state of rest for twelve, 

 and of exercise for twelve hours, and if the exercise is reduced to six 

 hours, the removal going on at the same rate for eighteen hours instead 

 of twelve hours will increase the exit of nitrogen 50 per cent. Ac- 

 cordingly during the period of rest the elimination of nitrogen increased, 

 and this was necessarily most marked during the first day, when the 

 bulk of the quiescent muscles was greater than on the second day, when 

 it had been reduced by excess of elimination. I do not see how pro- 

 perly to explain the increase during rest except in this way ; if the fact 

 be as I state it, no theory of muscular action can be true which does not 

 account for it. 



The effect on the reserve or store of nitrogen in the blood would be 

 to leave in it more nitrogen than usual at the end of the two days' rest. 

 The men then commenced ordinary occupation, and immediately the 

 muscles began again to contract and to assume more nitrogen in conse- 

 quence of the increased exercise. As they had to regain their former 

 composition, the elimination of nitrogen necessarily lessened, and the 

 reserve must have fallen to its normal amount. They would use up the 

 accumulation in the reserve as well as the fresh supply, and the equili- 

 brium would be restored ; this was nearly done in fact in twenty-four 

 hours, as may be seen in the Table. 



After four days the men took excess of exercise. The elimination of 

 nitrogen at once lessened, because more was used by the contracting 

 muscles, and there were lesser intervals of rest. 



