322 PHYSIOLOGY CHAP. 



be invoked in such transitory forms of glycosuria as are observed 

 in experimental nerve lesions (Bernard's puncture, ablation of 

 caeliac plexus, extirpations or lesions of different segments of the 

 central nervous system, etc.). In all these cases there is a rapid 

 glycogenesis of the glycogen of the liver, and in the absence of 

 glycogen, glycosuria (as we have seen) does not make its appearance. 

 This shows the possibility of its being due to the sudden hyper- 

 glycaemia induced by the entry into the circulation of the glucose 

 stored in the liver in the form of glycogen. 



The final conclusion which stands out from the mass of facts 

 we have been reviewing is that in pancreatic diabetes glycolytic 

 processes are reduced, although glycogenic processes are not 

 augmented. 



While not a few important questions remain wholly unsolved, 

 it is undeniable that experimental investigation of pancreatic 

 diabetes has thrown much light on the pathogenesis of spontaneous 

 diabetes, in which a more or less evident alteration of the 

 pancreatic parenchyma has been detected in all recent researches. 



XII. The Fats, absorbed in the form of soaps, regenerated by 

 the synthetic activity of the intestinal epithelia, and broken up 

 into minute droplets in passing through the walls of the central 

 lacteal of the villi, are (as we have seen) poured out by the thoracic 

 duct into the blood torrent, where they give a more or less milky 

 aspect to the blood plasma according as the diet has been more or 

 less rich in fats. 



After a short time, however, the fat content of the blood, 

 which may immediately after absorption amount to 1 per cent of 

 the total mass of the blood (and even exceed it, up to a maximum 

 of 6 per cent according to Bleibtreu) becomes much diminished, 

 till shortly before a meal, and in a prolonged fast, traces only of 

 fat are left in the blood plasma (Vol. I. p. 130). When but 

 little fat is given with the food, it is evidently consumed during 

 the day, perhaps within the blood, either by direct oxidation, or in 

 consequence of the katabolic activity of the leucocytes of the blood 

 and lymph. These always contain a certain amount of fat globules 

 ingested by the phagocytes, which can be distinguished from the 

 protoplasmatic granules by the fact that they discolour in ether 

 and stain black with osmic acid. After a plentiful meal of fat, 

 however, the fat escapes to a great extent from the blood, and is 

 stored up in the tissues as a reserve material, as we found to be 

 the case with the carbohydrates. 



We are wholly ignorant of the mechanism by which the fats 

 leave the blood, and penetrate to the interior of the tissue cells. 

 Since fat must be decomposed and saponified before it can be 

 absorbed by the epithelium of the intestine, it is probable, according 

 to Altmann, that cleavage is again required before it can leave 

 the blood and penetrate into the tissues, which must be followed 



