THE PHOSPHATES. 223 



decided alkaline reaction, whilst the juices of the most vitally 

 active organs have a decided acid reaction. Besides the blood, 

 there are only few of the animal fluids which are constantly alka- 

 line, as, for instance, the lymph, the chyle, and the transudations. 

 Among the secretions, the saliva alone exhibits a strongly alkaline 

 reaction under certain physiological conditions, whilst the bile and 

 the pancreatic juice are so slightly alkaline that they are often 

 unable, under ordinary conditions, to neutralize the acid masses 

 which enter the duodenum from the stomach. On the other 

 hand, we know to what a degree the gastric juice is distinguished 

 for its acidity, and that the acidity of the muscular juice varies 

 directly with the activity of the corresponding organs ; the most 

 recent experiments of Du Bois Reymond and Liebig showing that 

 the muscles, when at rest, contain no acid juice. The paren- 

 chymatous fluids of the spleen, the thymus gland, the smooth 

 muscles, the liver, and the supra-renal capsules, all contain free 

 acid. This antithesis in the preponderance of the alkali and the 

 acid is not only apparent in the mass of the coarser organs, but 

 shows itself on a close examination even where we should not 

 expect to meet with such differences, as for instance, in the egg and 

 the blood. Although the fluid of the yolk exhibits no acid reaction 

 towards vegetable colours, yet it is found, on a closer examination, 

 to differ essentially from that of the white, which is so rich in 

 albuminate of soda and alkaline carbonates as always to colour 

 turmeric brown, whilst the yolk-fluid is so poor in alkalies that 

 the casein contained in it is separated in granules. We might 

 certainly regard this casein as the free acid of the yolk, if the ash- 

 analyses of the latter did not show that the mineral bases are 

 insufficient to saturate half of the phosphoric acid contained in it 

 (see vol. ii, p. 360). In examining the blood, we find that a 

 difference exists between the serum and the blood-cells precisely 

 similar to that which we have noticed between the yolk and the 

 white of the egg. If we are not mistaken, C. Schmidt has some- 

 where suggested that the contents of the red blood-cells may have 

 an acid reaction ; the numerous experiments which I have made 

 in relation to this question have not enabled me to arrive at any 

 definite results ; but if we consider the composition of the mineral 

 constituents belonging to the blood-cells as first determined by 

 Schmidt, and if we bear in mind the facts* which have been recently 

 established regarding the behaviour of the crystalline substance 

 of the blood, its acid reaction on coagulation, the amount of 



* [See note to vol. ii, p. 185, (on the crystalline matter contained in the blood- 

 cells) in the Appendix.] 



