REGULATION OF CELL ACTIVITIES 199 



substance is then given, and it is seen if there is 



of extra sugar. If more sugar is formed the XT ratio may 



D 



alter. If the N ratio does not alter the extra sugar may be 



due to an extra breakdown of protein, so it is important to 

 compare the ratio with the ratio of the amount of sugar 



which can be formed from the carbon to the nitrogen of the 

 substance administered. 



Sugar has been shown to be formed from glycerine, glyceric 

 acid, lactic acid, propyl alcohol, glycocoll, alanine, aspartic 

 acid and glutaminic acid. 



TABLE XXXVII 

 F ormation of Glucose from Amino Acids in Animal Metabolism. 



From Graham Lusk, pp. 381 and 382. 



Nervous Glycosuria. Claude Bernard, about 1850, showed 

 that injury to the medulla causes glycosuria.* He ascribed 

 this to the presence of a diabetic centre in the medulla. It 

 seems that this form of glycosuria is brought about through 

 the splanchnic nerves which act upon the liver, upsetting the 

 normal glycogenic function. Administration of adrenaline 

 produces glycosuria, probably by stimulation of the splanchnic 

 nerve endings. 



Glycosuria can be brought about by anaesthetics, asphyxia and 

 other agents. Some animals are more easily affected than others. 



The internal secretions affect the metabolism and numerous 

 observations on nitrogenous and carbohydrate metabolism 

 have been made. Presence or absence of some of these 

 hormones produces glycosuria or increase the sugar tolerance, 

 the details of which must be found elsewhere. 



Other organs furnish internal secretions, but in many cases 

 the observations have not reached the stage in which they can 

 be considered from the chemical point of view, but a few 

 examples will be of interest. 



The development of the mammary glands has been shown 



* Claude Bernard, Lefons dephysiol. exptrimentale, Paris, 1855, p. 289. 



