232 BLOOD. 



fluid in diseases, since they have not led to such complete and 

 available results as to justify us in more fully noticing this subject 

 without some deeper insight into the individual pathological 

 processes. 



Very little is known regarding the alterations which the chemical 

 composition of the blood-corpuscles undergoes under different phy- 

 siological and pathological relations, since no light has hitherto 

 been thrown upon their morphological condition ; enquirers having 

 limited themselves to an attempt to determine the frequently men- 

 tioned dry blood-corpuscles, without reference to the water apper- 

 taining to them, or to the soluble constituents which they may con- 

 tain. If we were to attempt to calculate these relations from the older 

 analyses, we should readily be led into error, even if our calculations 

 were not wholly impracticable ; since all the relations cannot be 

 taken into account when we draw deductions from an investigation 

 which has been entered upon from wholly different points of view. 

 We regard a mere re-calculation of the analyses as of little or no 

 use, unless they are tested by others conducted by better methods, 

 and prosecuted from a different point of view. Science presents 

 therefore, very few materials for the comprehension of the modifi- 

 cations exhibited in the composition of the blood-corpuscles. 



The amount of water in the blood- cells undoubtedly stands in a 

 definite relation to the amount of water in the serum, as we may 

 easily perceive from the morphological behaviour of the blood -cells 

 on the addition of water, or dilute or concentrated saline solutions. 

 In this point of view, the blood-cells, moreover, are constantly 

 reacting on the intercellular fluid. Then, further, it is easy to 

 perceive that the constituents of the blood-cells, which differ 

 essentially from those of the plasma, must also have different 

 degrees of diffusibility for water ; and that the quantity of water 

 contained in the blood-cells must always differ from that in the 

 intercellular fluid. We have already seen, from Schmidt's investi- 

 gations, that the solid constituents of the blood-cells are almost 

 four times as great as those of the serum; that is to say, if 100 

 parts of blood-cells contain 32 solid parts, we shall find in 100 

 parts of serum little more than 8 parts of solid matter. In the 

 meanwhile, the most accurate of Schmidt's investigations regarding 

 human blood, and of my own, on the blood of the horse, by no 

 means present a constant relation between the quantity of water 

 contained in the blood-cells and that in the serum ; but such a 

 result was not to be expected from the differences which the cells 

 present in their chemical constitution. This much only is certain, 



