290 



Accordingly, having received the kind offer of Professor Sharpey's 

 cooperation, I undertook a series of experiments, the results of which 

 I beg the honour of communicating to the Royal Society. 



As the experiments performed were merely a repetition of some 

 of those made by previous inquirers, I shall not enter into detail 

 further than is necessary to explain the precautions adopted with the 

 view to avoid error. And, looking at the object in view, it will 

 readily be understood why in the present instance the tests employed 

 for the detection of the sugar were limited to caustic potash with 

 and without sulphate of copper. The mode of proceeding was as 

 follows : In testing the blood, a quantity of distilled water, equal 

 to about four times that of the blood used, was boiled in a capsule. 

 To the water, when boiling, were added a few drops of acetic acid, 

 and afterwards the blood was very gradually introduced. In order 

 that the albumen might be thoroughly coagulated, a drop or two more 

 of acetic acid was added, care being taken to avoid an excess. When 

 the albumen was completely coagulated, which was known by its 

 separating and floating in the clear liquid, the whole was thrown on 

 a filter. The clear filtered liquid was then tested. The same pro- 

 cess was followed when operating on the liver. 



The first point to be ascertained was whether, under favourable 

 circumstances as regarded diet, sugar could be found in the circula- 

 tion. The following experiment proved this. 



Exp. 1. From the carotid artery of a rough terrier dog, three 

 hours after being fed on bread, milk, and boiled liver, a portion of 

 blood equal to about three-fourths of an ounce was withdrawn. 

 This, on being treated in the manner explained, gave distinct 

 evidence of the presence of sugar. A second portion of blood, after 

 standing thirty-five minutes in a room of moderate temperature, 

 yielded a similar re&ult. 



As in this instance a few seconds elapsed between the withdrawal 

 of the first portion of blood and its treatment with the boiling acidu- 

 lated water, and as it was possible that in these few seconds the sugar 

 might have been formed from the glucogen present in the circulation, 

 we (Professor Sharpey and myself) thought it advisable in our next 

 experiment to allow the blood to flow directly from the artery into the 

 boiling mixture, and thereby avoid the possibility of sugar being pro- 

 duced by the transformation of glucogen after the removal of the blood 



