522 



Dr. F. W. Pavy oh the 



[Apr. 24, 



taining the suboxide in the dissolved state, a reducing substance 

 becomes developed, or else that the amount of oxide of copper appro- 

 priated to the oxidation of the sugar becomes altered in the presence 

 of the large amount of potash which it is necessary to employ. 



Lastly, it may be observed that a close conformity exists between 

 the figures in columns 4 and 5. The results obtained by the gravi- 

 metric method are thus confirmed by the volumetric results obtained 

 by means of the ammoniated form of the cupric test. Seeing that 

 separately prepared specimens of the respective samples of blood were 

 submitted to the two kinds of analysis, the conformity is certainly 

 striking, and gives strong weight to the validity of the results yielded 

 by the gravimetric method. 



One of the points referred to in my second communication * is the 

 spontaneous disappearance of sugar from the blood after withdrawal 

 from the body. It is a part of Bernard's doctrine that the natural 

 seat of destruction of sugar within the system is in the systemic 

 capillaries, and if it can be shown that an active disappearance of 

 sugar occurs in the blood after removal from the vessels, support is 

 given to his proposition. I cited the observation which has been 

 adduced by Bernard to illustrate that a marked aptitude exists for the 

 disappearance of sugar under the circumstances named. According to 

 this observation, a reduction from 1*070 to 0*880 parts per 1,000 

 occurred during the first half -hoar, and at the end of 24 hours the 

 analytical result obtained is represented as standing thus — O'OOO. I 

 stated that my own experience furnished evidence of a widely different 

 nature, and introduced the figures yielded by five observations in proof 

 of this assertion. 



The gravimetric process is only suited for the examination of blood 

 before decomposition has set in, as the result would be vitiated 

 by the presence of ammonia as a product of decomposition, the effect 

 being an interference with the deposition of the cuprous oxide. With 

 the ammoniated cupric test, however, any state is suitable ; and since 

 my communication of June 21st, 1877, was published, I have applied 

 this process, as well as Bernard's potash process, to blood which has 

 been kept for lengthened periods, instead of limiting the examination, 

 as I had previously done, to the first twenty-four hours. The results 

 obtained were quite unlooked for, and quite irreconcileable with the 

 representation in Bernard's observation, which has been referred to, 

 that at the end of twenty-four hours the blood ceased to give any 

 indication of the presence of sugar. 



I have before me a large amount of recorded experience, but need 

 only select a few illustrative examples, for the information supplied is 

 of the same nature throughout. In no case, although the blood had 

 acquired a highly offensive character from putrefaction, has it failed to 

 * " Proc. Roy. Soc," vol. xxvi, p. 346. 



