54* METABOLISM, NUTRITION AND DIETETICS 



destroyed, or that it may pass from the blood, without being oxi- 

 dized, into the lymph, too much weight may be easily given to the 

 results of direct analysis of the in-coming and out-going blood. 

 And although the results of Chauveau and Kaufmann, obtained in 

 this way, fit in fairly well with what we have already learnt by less 

 direct, but more trustworthy, methods, such as the study of the 

 respiratory exchange, they cannot be accepted as yielding exact 

 quantitative information. They found that in one of the muscles 

 of the upper lip of the horse the quantity of dextrose used up during 

 activity (feeding movements) was 3-5 times as much as in the same 

 muscle at rest, and this corresponded with the deficit of oxygen in 

 the blood entering the muscle, and with the excess. of carbon dioxide 

 in the blood leaving it. More dextrose was also destroyed in the 

 active than in the passive parotid gland of the horse, but the excess 

 per unit of weight of the organ was far less than in muscle. In dogs 

 whose abdominal viscera have been removed, so that they constitute 

 practically preparations composed of skeletal muscles it has been 

 found that the amount of dextrose which disappears from 100 grammes 

 of blood per minute varies from 0-47 to 1-8 milligrammes, the irregu- 

 larities probably depending largely upon the irregular consumption 

 by the muscles of the glycogen stored in them (Macleod and 

 Pearce). 



Intermediary Metabolism of Carbo- Hydrates. Concerning the pro- 

 cesses and the stages by which dextrose is destroyed in the tissues, 

 we have no very exact information, and it cannot be definitely stated 

 at present what share is taken by cleavage and what by oxidation, 

 or rather through what intermediate products, formed, it may be, 

 now by simple cleavage, now by oxidation, again by a combination 

 of cleavage and oxidation, the dextrose molecule is finally resolved 

 into carbon dioxide and water. It must be remembered that the 

 synthetic powers of animal cells are now known to be very extensive. 

 They build carbo-hydrates, fats, phosphatides, and proteins, as 

 well as destroy them, and at any of the earlier stages at any rate 

 the degradation products of dextrose, or some of them, may be 

 utilized in the construction of new compounds for example, of fat 

 either in the cells where they arise or elsewhere in the body. In 

 like manner the decomposition of a molecule of dextrose begun in 

 one cell or in one tissue may be consummated in another to which 

 intermediate products are conveyed in the blood. In such ways 

 it is obvious that the katabolic processes may be finely regulated 

 both qualitatively and quantitatively in accordance with the 

 specific wants of different organs and the intensity of their func- 

 tional activity from time to time. It must be said, however, that 

 at present there are few definitely ascertained facts to guide us in 

 trying to form a scheme of the actual changes which occur in the 

 intermediate katabolism of carbo-hydrates, and the sequence which 



