06 Dr. Mitchell on (he Occurrence of Sugar in tJie Animal Economy. 



of water. Again, when sugar is subjected to the action of alkalis, a whole 

 series of different new products is obtained ; while oxidising agents, such 

 as nitric acid, produce from sugar carbonic acid, acetic acid, oxalic acid, 

 formic acid, and many other products not yet examined. If, fi-om the 

 facts here stated, we estimate the power with which the elements of sugar 

 are united together, and judge of the force of their attraction by the 

 resistance which they offer to the action of bodies brought into contact 

 with them, we must regard the atom of sugar as belonging to that class 

 of compound atoms which exist only by the vis inertife of their elements. 

 Its elements seem merely to retain passively the condition in which they 

 have been placed." 



It has been shown that the blood of animals contains sugar ; and the 

 same substance, as is well known, exists also in the sap of plants. Instead, 

 however, of being destroyed and disappearing from the sap of plants, we 

 find it deposited in some particular part, or aggregated in the general 

 tissue. Now, in what respects does the sap of vegetables most ostensibly 

 and uniformly differ from the blood of animals? When in a healthy 

 condition the blood is an alkaline fluid, while the sap of such plants is 

 either neutral or acid, and never alkaline. But will the difference in this 

 property account for the destruction of the sugar in the one case, and its 

 being hoarded up in the other? Let us change the respective conditions 

 and mark the effect. 



If the acidity of the sap of the vegetable be modified by watering it 

 with a slightly alkaline solution, it acquires chemical properties analogous 

 to those of the blood, and we find, as an apparent result, that the sugar 

 is destroyed as rapidly as formed, that the secretions are no longer sac- 

 charine, and that it no longer bears sweet fruits. This fact has been 

 established by JI. Fremy. 



And now, in cases of diabetes, where sugar, ceasing to be destroyed, 

 passes off in the urine, let us inquire, if the change this supposition would 

 predict has really taken place — if, instead of being alkaline, the blood is 

 neutral or acid. 



We find certainly the saliva of diabetes acid, and the humours generally 

 more acid than normal ; but with regard to the blood, I believe that in 

 this disease it is often found neutral, very rarely acid, and generally 

 alkaline. It may still, however, be that the alkalinity is diminished in 

 degree, and in this manner its healthy functions may be impeded, suf- 

 ficiently to give serious results. 



These facts, standing alone, incline us] to suspect that the alkaline 

 condition of the blood is active in effecting the destruction of the sugar, 

 either in part or in whole ; and here, in the meantime, I shall quit the 

 consideration. 



Do we derive any information on this subject from comparative analyses 

 of blood from different sources ? I fear not, from any hitherto performed, 

 which are suflSciently extensive and accurate to yield a fair average and 

 authorize a deduction. I shall briefly state, however, the averages of 



