212 BLOOD. 



Other substances occurring in the serum of normal blood are 

 urea, (see vol. i. page 164), uric acid, (vol. i. page 217), and 

 hippuric acid. The latter has been found by Verdeil and Dollfuss* 

 at Giessen, in the blood of oxen. That creatine and creatinine 

 occur in the blood, has certainly not yet been proved by direct 

 investigation, but from the simultaneous occurrence of these two 

 substances in the muscular juice and in the urine, we are justified 

 in concluding that they exist there. 



Whether biliary matters, to wit, the biliary acids, occur pre- 

 formed in normal blood, we have not at present the means of 

 deciding (as has been already mentioned in page 81) ; on theo- 

 retical grounds, we should, however, regard their presence as 

 improbable. 



We are still perfectly in the dark regarding the pigments of 

 normal serum (see vol. i. page 299). 



The faint yellow colour which is peculiar to normal serum, 

 certainly does not depend on bile-pigment ; at all events, we 

 cannot exhibit the well-known and striking reactions of chole- 

 pyrrhin with the extracts of the serum. In diseases, the serum 

 often assumes an intense yellow colour, with or without simultaneous 

 turbidity ; this depends either on bile-pigment, which is recognis- 

 able in the blood, not merely in icterus, but sometimes also in 

 cases of pneumonia, or on an augmentation of the above-mentioned 

 little understood serum-pigment, (which is also most frequently 

 observable in inflammatory processes), or lastly, on suspended blood- 

 corpuscles. Schultz is of opinion, that hsematin may also occur in 

 solution in the serum, if the contents of the blood-cells become 

 diffused in it, in consequence of a deficiency of salts in the blood. 

 Such cases must, however, be very rare. 



We have little to add to what has been already stated, regarding 

 the salts peculiar to the serum (see vol. i., p. 4Sl,and p. 189 of 

 this volume). While phosphates and potash-salts predominate 

 in the blood-corpuscles, we find a preponderating quantity of 

 soda-salts, and especially of the chloride of sodium, in the serum ; 

 on an average we also find far more salts in the serum than in the 

 blood-cells (after deducting the iron). Alkaline sulphates and car- 

 bonates belong also principally to the intercellular fluid. 



Before concluding our remarks on the qualitative examination 



of the blood, we must mention the persistent odour which is 



peculiar to that fluid, and which is particularly evolved on mixing 



blood with a larger quantity of sulphuric acid, as for instance, 1 



* Compt. rend. T. 30, p. 510 et 657660. 



