METABOLISM. 37 
animal receiving food, the liver breaks down the proteids and fat 
supplied to the blood either by the food or from the tissues, pro- 
ducing dextrose. This dextrose, like that derived from the carbo- 
hydrates of the food, is then, as indicated in the previous section, 
oxidized in the tissues either directly or with previous conversion 
into glycogen. 
As regards the katabolism of fat, in particular, Nasse * has 
brought forward reasons for believing that the liver is concerned in 
it. Seegen T submitted fat to the action of finely chopped, freshly 
excised liver suspended in defibrinated blood at a temperature of 
35-40° C., in a current of air and observed a considerable formation 
of sugar in five to six hours as compared with a control experiment 
without the fat. He likewise found { in experiments upon dogs 
fed on fat with little or no meat that the blood of the hepatic vein 
was much richer in sugar than that of the portal vein. On the basis 
of the probable amount of blood circulating through the liver, he 
computes that the total amount of sugar thus produced was much 
greater than could have been supplied by the glycogen stored in 
the liver and the amount of proteids metabolized (as measured 
by the urinary nitrogen), and hence concludes that at least the 
difference was produced from fat. As was pointed out in the 
preceding section, however, many physiologists regard the large 
differences between the dextrose content of the portal and the 
hepatic blood observed by Seegen as being in large part the result of 
the necessary operation and thus abnormal, and the production of 
glycogen or dextrose from fat is not regarded as proven by the 
majority of physiologists.§ Thus Girard || and Panormow {| found 
the post-mortem formation of sugar in the liver to be strictly pro- 
portional to the disappearance of glycogen, and similar results 
were obtained by Cavazzani and Butte.** 
Kaufmann,tt+ who has developed this hypothesis in considerable 
* y. Noorden, Pathologie des Stoffwechsels, p. 85. 
+ Die Zuckerbildung im Thierkérper, p. 151. 
t Ibid., p. 171. 
§ Cf. Neumeister, Physiologische Chemie, p. 368. 
| Arch. ges. Physiol., 41, 294. 
{ Thier. Chem. Ber., 17, 304. 
** Ibid., 24, 391 and 394. 
+t Archives de Physiol., 1896, p. 331. 
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