234 METAMORPHOSIS OF TISSUE. 



is solely owing to the blood not being sufficiently rich in alkali to 

 aid in the oxidation of the sugar. With a view of determining 

 this point, I injected caustic alkalies or their carbonates, in 

 association with grape-sugar, into the veins of rabbits ; but even in 

 these experiments the wholly unexpected result ensued that, not- 

 withstanding the caustic alkalies or their carbonates, the urine not 

 only contained sugar, but also exhibited an acid reaction. More 

 exact and often-repeated experiments on rabbits afforded the 

 following explanation of this remarkable phenomenon. When 

 1 equivalent of sugar with 1, 2, or 3 equivalents of caustic 

 potash or its carbonate, was injected, or when the sugar and 

 potash-compound artificially prepared from alcoholic solutions was 

 injected in such quantities that 0*1 of a gramme of sugar reached 

 the blood, the urine remained alkaline for at least ten minutes after 

 the injection, becoming then decidedly acid, in which state it con- 

 tinued for at least five hours, even when the animals had been fed 

 in the interval upon green food. In the seventh hour the free acid 

 diminished when food of this kind had been taken ; it continued, 

 however, although in a less intense degree, when the animals had 

 been kept fasting. In all cases, however, sugar could be detected 

 in the urine from the first five minutes after the injection to the 

 eighth, and even often to the eighteenth hour. If in these cases 

 the alkali does not act in the manner one might be led to expect 

 from the above hypothesis, the cause is to be ascribed partly to 

 the circumstance that the alkali is removed from the blood more 

 rapidly than the sugar, and partly, and perhaps mainly, to the fact of 

 an acid being formed in the blood (as we see by the constant acid 

 reaction of the urine after the injection of sugar) by which the alkali 

 is saturated, and its action on the sugar thus interfered with. I 

 have unfortunately been unable, from the small amount of material 

 for investigation, to decide what is the acid which is thus produced, 

 but it certainly is neither phosphoric or hippuric acid. We at all 

 events learn this much from these experiments, that no one 

 perfectly correct chemical fact can enable us to foresee and cor- 

 rectly prejudge the result of chemical effects in the living body ; 

 and it would, therefore, be no less unsuitable to endeavour to 

 elucidate the mystery of life by rude chemical hypotheses, than it 

 would be senseless to banish chemistry from the sphere of vitality 

 merely on account of some few unsuccessful experiments. The 

 following experiments, which I have instituted in relation to this 

 point, will show the correctness of these views. On gradually 

 injecting very dilute solutions of tartaric and citric acids into the 



