BY DR. LAUDER BRUNTON. 513 



160. Separation of a Diastatic Ferment from the 

 Liver. Cut off the head of a rabbit and remove the liver as 

 quickly as possible. Mince it and wash it with water several 

 times to remove the blood. Then squeeze it tolerably dry, put 

 it into absolute alcohol, and let it remain for twenty-four 

 hours. Filter off the alcohol, wash the liver with alcohol, and 

 then put the mass, for several da}'s, in gtycerin. Filter it 

 through muslin. The filtrate is free from sugar, but contains 

 a ferment which converts glycogen and starch into sugar. 

 Take a little of the glycerin extract in each of three test- 

 tubes ; put into one a little glycogen, and into another a little 

 starch paste, and let them stand for a quarter or half an hour. 

 Then test all three for sugar with copper sulphate and potash. 

 No sugar will be found in the tube containing the glj-cerin 

 extract alone, the sugar found in the liver immediately after 

 death having been removed by the alcohol before the glycerin 

 was added. Both the other tubes will contain sugar. Diluting 

 the glycerin extract does not alter the effect. 



After the Ferment has been extracted by Glycerin, the Jfa.s.s 

 atill contains Glycogen. Extract the mass several times with 

 fresh glycerin. Take two test-tubes: then introduce a little of 

 it, with water in each, and let them into two test-tubes. Test 

 one of them for sugar: none is found. Add to the other one 

 a little of the glycerin extract, which has already been found 

 to contain no sugar, and let it stand at 40 C. for some time, 

 after which it will be found to contain sugar. A similar 

 ferment can be extracted from bile by precipitating it with 

 alcohol, washing the precipitate with alcohol on a filter, and 

 then extracting it with glycerin in the way already mentioned 

 (Von Wittieh). 



161. Glycosuria. It is still disputed whether sugar is a 

 normal constituent of the urine or not. But in the diseased 

 condition, to which the term Diabetes Mellitas is applied, it 

 appears in considerable quantities. Bernard first showed that 

 its appearance in the urine can be induced by certain lesions 

 of the nervous system, and finding that they caused, at the 

 same time, dilatation of the vessels of the liver, he attributed 

 the appearance of the sugar to the increased circulation 

 through that organ. His views have lately been confirmed; 

 the nervous mechanism by which the vessels become dilated 

 has been discovered by Cyon and Aladoff, from whose re- 

 searches it appears that the vasomotor nerves of the hepatic 

 vessels pass from the vasomotor centre in the medulla oblon- 

 gata down the cervical part of the spinal cord, which they 

 leave at its lower end. Thence they accompany the vertebral 

 arteries to the Jast cervical ganglion, finding their way by the 

 two fibres, which pass in front and behind the subclavian 

 artery (forming the annulus of Vieussens) to the first dorsal 



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