928 SPECIAL PHYSIOLOGY. 



The exact destination of the potential energy, liberated by the 

 double process of oxidation of nitrogenous and non-nitrogenous mate- 

 rials, which, undoubtedly takes place in muscular motion, cannot at 

 present be precisely pointed out. In Man, the latter substances 

 undergo far more abundant decomposition than the former, and, as 

 remarked by Frankland, whilst the nitrogenous materials are only 

 partially oxidized, being discharged as urea, and retaining about ^th 

 of their potential energy unexpended, the non-nitrogenous substances 

 yield all their energy in the body, being oxidized perfectly as carbonic 

 acid and water. 



There are many facts which indicate the necessity for large amounts 

 of non-nitrogenous food, for the due performance of muscular work. 

 It is in the larval stage that Insects generally consume the most 

 albuminoid food, and perform the least amount of work, whilst, in the 

 perfect condition, as in bees, butterflies, and moths, their muscular 

 activity is remarkable, although their food is almost purely saccharine 

 or non-nitrogenous. (Yerloren.) The goat, chamois, gazelle, and many 

 other Ruminants, are singularly swift and active creatures ; their food, 

 however, is not highly nitrogenous, but chiefly consists of carbhydrates. 

 It is not probable that the muscular work in any of these cases is 

 performed by the oxidation of albuminoid matters only; for, in that 

 event, the muscles, especially the minute ones of Insects, would soon 

 be entirely oxidized, and could not be restored by the scanty supply 

 of nitrogen in the food. The remarkable provisions for digesting the 

 carbhydrates and rendering them absorbable, appear therefore to have 

 reference, not only to their use as heat-givers, but also as sources of 

 motor power. The production of sugar from starch, is a universal 

 action of the saliva of all animals, and long-continued digestion in the 

 Ruminant stomach will even change the cellulose. It has been re- 

 marked, that the chief food-manufactures are concerned with non- 

 nitrogenous articles of diet ; that eggs contain, when dried, 40 per 

 cent, of fatty matter ; that fat is always present in meat ; that the poor 

 consume much bacon-fat ; and the rich, who eat most albuminoid food, 

 likewise take more butter, sugar, and alcohol. (Lawes and Gilbert.) 

 The use of bacon by the agricultural laborer, has given rise to a 

 familiar epithet for him. The chamois-hunters prefer a store of bacon- 

 fat and sugar, to any other provisions, on a hunting expedition ; and 

 Fick and Wislicenus ascended the Faulhorn on non-nitrogenous diet, 

 without special fatigue. But, on the other hand, Parkes found, that 

 on the second day of severe exercise, on a non-nitrogenous diet, healthy 

 soldiers complained of unusual fatigue. Practically, it would seem 

 that sufficient nitrogenous food being supplied for the nutrition of the 

 muscular and nervous system, then the most effective diet for a laborer 

 is that which contains a large proportion of non-nitrogenous substances. 

 Athletes should train on meat, but enter into their contests upon 

 amylaceous, saccharine, or fatty food. 



Dr. Frankland has extended his method of determining the heat- 

 units by deflagration with chlorate of potash, to various articles of 

 diet, in order to test, in this way, their mechanical equivalents, or 

 motor values. The actual energy of a given weight, 1 gramme, of each 



