INTERMEDIATE METABOLISM OF CARBOHYDRATES 395 



energy, the muscular tissues may not be able to utilize proteins for the 

 performance of mechanical work. Experiments of Kellner, conducted 

 upon horses, render this very probable, for this observer found that 

 while muscular work upon a mixed diet, as Voit had previously shown, 

 does not increase the nitrogenous output of the horse, yet muscular 

 work upon a diet which contained an insufficient allowance of carbo- 

 hydrates did result in a notable increase of nitrogen elimination. This 

 fact may be paralleled by the oft-repeated observation that while 

 Bacteria will preferably obtain their energy from carbohydrates in the 

 culture-medium, yet if these be insufficient in amount, proteins are 

 attacked and energy is derived from the hydrocarbon radicals which 

 they contain, nitrogenous fragments being split off as by-products of 

 the process. 



Now proteins, being an abnormal source of muscular energy, may 

 very possibly give rise to some unusual products when necessity com- 

 pels their utilization for this exceptional purpose. We recognize that 

 the protein metabolism of muscular tissues is peculiar. The abundance 

 of Creatine in the muscles and the presence of Methylguanidine, Dimethyl- 

 guanidine, Carnitine and other physiologically active nitrogenous bases 

 in muscular tissues show that the degradation of protein in these 

 tissues does not follow the channels normal to other tissues, and arouses 

 the suspicion that rapid and extensive breaking-down of muscle-pro- 

 teins might lead to the production of toxic bases in dangerous amounts 

 and to notable physiological disturbances. We are reminded, in this 

 connection, of the fact that the dangerous toxemia of pregnancy, 

 Eclampsia, is often accompanied by sudden involution (degeneration) 

 of the muscular tissues of the uterus. Nor are there wanting facts 

 which tend directly to show that extreme muscular exhaustion upon 

 a high protein diet may be dangerous. The experiences of Mawson 

 and Mertz in the Australian Antarctic expedition of 1912-1913, which 

 culminated in the tragic death of Dr. Xavier Mertz, may be instanced. 

 In severe antarctic weather and heavily crevassed country, involving 

 extraordinary expenditures of energy to maintain bodily heat and make 

 progress over the ground, at a distance of three hundred miles from 

 headquarters, these explorers, through loss of a companion and a 

 sledge in a crevasse, found themselves with a bare one and a half weeks' 

 food for themselves, and none at all for the dogs. They started to 

 walk back to their headquarters, killing the dogs from time to time and 

 consuming their necessarily excessively lean flesh. After eighteen 

 days Mertz began to fail, and during several days expressed especial 

 aversion to the dogs' meat; he displayed great muscular weakness, 

 and complained of Violent abdominal pains from which Mawson also 

 suffered. Seven days later symptoms of central nervous intoxication 

 appeared. The following are notes from Mawson's diary: 



"January 7. It was a sad blow to me to find that Mertz was in a 

 weak state and requited helping in and out of his bag. He needed 

 rest for a few hours at least before he could think of travelling. I have 



