METHODS OF ANALYSIS. 219 



solution of pure sulphate of soda. Hence, notwithstanding the 

 most careful washing, substances are added by the serum to the 

 corpuscles. Moreover, in examining the ash of the bloodrcells 

 determined by Hofle's method, Hinterberger found a large amount 

 of sulphates. This, however, I have never observed when the 

 coagulum was properly washed with hot water. But, on carefully 

 considering the application of this method, we find that in theory 

 also there are certain objections to it. Thus, if we wash the blood- 

 corpuscles with a fluid which leaves the walls of the cells unin- 

 jured, the permeability of the walls is not by that means impeded. 

 We know that the soluble salts of the blood-cells permeate the 

 cell-walls ; hence it would be very remarkable if the soluble 

 coagulable protein-bodies of the cell-contents could not also 

 partially penetrate the cell-membranes after the removal of all the 

 serum, in accordance with the laws of endosmosis. Moreover the 

 substance retained in the blood-corpuscles (as C. Schmidt has 

 shown) loses potash by its solution in water and subsequent coa- 

 gulation, and besides this also organic matter ; so that this method, 

 even if all- the serum could be removed from the blood-corpuscles, 

 would prove insufficient to determine the solid constituents of the 

 blood-cells. 



C. Schmidt* is the first who has attempted the solution of the 

 problem, to determine the relation of the moist blood-cells to the 

 intercellular fluid. His mode of proceeding is not based, as might 

 be supposed, on the direct determination of the dry blood- 

 corpuscles by means of sulphate of soda, but, on the contrary, on 

 the original method of Prevost and Dumas. Since the investi- 

 gations of the most accurate analysts show that the solid con- 

 stituents of the serum stand in a constant relation to those of the 

 clot, that is to say, since the richness of the clot in solid con- 

 stituents is proportional to the degree of concentration of the 

 serum, it follows that the number representing the dry blood- 

 corpuscles, calculated according to Prevost and Dumas' method, 

 must also stand in a constant relation to the fresh corpuscles 

 existing; in the blood. It thus became necessary to discover the 

 constant factor by which we might calculate the blood-cells (in the 

 morphological sense) from the hypothetical dry blood-corpuscles 

 found by Prevost and Dumas' method. Schmidt has found that 

 this coefficient is equal to 4, so that we have only to multiply the 

 hypothetical dry blood-corpuscles by 4, in order to obtain the 

 number representing the moist blood-cells. Schmidt's experi- 

 ments show that a number, larger or smaller by 0*3 than 4*0, fails 

 * Charakteristik der Cholera. S. 319. 



