358 VETERINARY PHYSIOLOGY 



(ii) Nor are the fats fully available, because the 

 metabolism of carbohydrates is necessary for their combus- 

 tion, and this is in abeyance. As a result of this incomplete 

 metabolism of fats, ^-oxybutyric acid is produced, which 

 leads to a decrease in the alkalinity of the blood and tissues, 

 to a condition of acidosis. 



The ^-oxybutyric acid is not oxidised to COo and HoO 

 as it normally is, but is converted to diactic acid, and this 

 in turn to acetone, and these bodies may be detected in the 

 urine (Chemical Physiology). 



/3-Oxybutyric Acid . CHg.CH.OHiCH.CO.OH 



Diacetic Acid . . CH3CO.CH2CO.OH 



Acetone . . . CH3CO.CH3. 



Hence, in fully-developed pancreatic diabetes, none of the 

 proximate principles of the food yield the energy required, 

 and the animal or man rapidly becomes weak, emaciates 

 and dies. 



2. Regulation of the Supply of Fats- — (1) Storage The fats 



leave the intestine not by the blood of the portal veins 

 which goes straight to the liver, but through the lymphatics 

 which enter the blood stream, just where it returns to the 

 heart, through the thoracic duct. They thus reach the 

 liver by the arterial blood. Nevertheless, when taken in 

 excess of the immediate requirements, they are stored in 

 large amounts in the liver of some animals — e.g. the cod 

 among fish and the cat among mammals. Animals which 

 have little power of storing fat in the muscles and other 

 tissues seem to have a marked capacity for accumulating it 

 in the liver. Even in starvation, the fats do not disappear 

 from the liver, and throughout all conditions of life a fairly 

 constant amount of lecithin (p. 20) is present in the liver 

 cells. Lecithin, in the yolk of the egg, is an intermediate 

 stage in the formation of the more complex nucleins of living 

 cells ; and the formation of lecithin in the liver bv the 

 synthesis of glycerol, fatty acids, phosphoric acid, and 

 cholin is probably a first step in the construction of these 



