On the Non-existence of Sugar in the Blood. 



of diabetic persons, which I have mentioned to you at dif- 

 ferent periods, I am really ashamed to reflect how long I 

 have suffered them to remain neglected, when I consider - 

 their tendency to elucidate a curious point of physiological 

 research. 



Mv first endeavours to detect sugar in the serum of the 

 blood were made soon after perusing the second edition of 

 Dr. Rollo's Treatise on the Diabetes, (which was published 

 in 1798,) at the request of Dr. Baillie, who was so obliging 

 as to furnish me with various specimens of diabetic blood 

 and serum for this purpose. 



The other set of experiments which I made with reference 

 to the same question were not thought of till the following 

 year. The inquiry was then left unfinished, and 1 never 

 resumed it; for as I soon after* rchnquisUcd the practice 

 of physic, I desisted in a great measure from prosecuting 

 any inquiries connected with medicine. 



However, since so much of ibis subject as is strictly phy- 

 siological, relating to the natural course of circulating fluids, 

 and more especially so much of the investigation as is con- 

 ducted by chemical means, is within the range of those pur- 

 suits which are generally interesting to the Royal Society, 

 I will endeavour to give you as distinct an, account as I am 

 able of the progress of my own experiments, requesting 

 that you will in return state, more fully than you have hi- 

 therto done, the result of that further step in the inquiry 

 which you took at my suggestion; and if it is agreeable to 

 you, we will without delay make a joint communication ofj 

 our researches to the Society. 



Although Dr. Rollo had been assisted in the chemical 

 part of bis inquiry by the well-known talents of Mr. Cruick- 

 sbank, it appears that they " had not been so fortunate as 

 to obtain a sufficient (piantitv of serum for chemical ex-t 

 perimentt;" and were unable fully to satisfy themselves, by 

 the. taste or bv other means which they could employ, con- 

 cerning the existence or non-existence of sugar in the blood 

 of persons labouring under diabetes ; but nevertheless they 

 were persuaded of its presence. 



For the purpose of forming some judgement on this 

 question, Mr. Cruickshank made trial of the quantities of 

 oxalic acid that could be formed from serum or from blood 

 jn their natural state, and i'rom the same serum or blood 

 alter the addition of a certain proportion of sugar; and 

 from the diffei^nce perceptible in these trials, he formed a 



* In 1800. f Rollo on Diab«tei, p. 408. 



B 2 probable 



