526 APPENDIX. 



is anything more than albuminate of potash or soda. See vol. i, 

 p. 334. 



(23) Addition to p. 224, 15 lines from the bottom. Vierordt,* 

 has recently succeeded, by means of very comprehensive and un- 

 usually laborious investigations, in sketching a method of a blood- 

 analysis, which promises to supply some of those deficiencies in 

 Schmidt's method, which have been felt by all experimentalists, 

 and may therefore serve in some degree at least as a check upon 

 the latter. If we were able to determine the numerical quantity 

 and the volume of the blood-corpuscles in every kind of blood to 

 be analysed, we should naturally have no difficulty in obtaining 

 their relations of weight in the blood, and of determining by a 

 simple calculation from the further analysis of the blood the 

 amount of constituents appertaining to the blood-corpuscles. 

 Vierordt was thus led, at the expense of much time and labour, 

 to calculate the number of the blood-corpuscles in the two follow- 

 ing ways. In the one method, a small volume of unmixed blood 

 was measured in a capillary tube, and then introduced into what he 

 termed a diluting fluid (a tolerably concentrated solution of albu- 

 men or gum), with which it was spread out under the microscope, 

 and the corpuscles were then counted by means of two glass 

 micrometers, which had been graduated expressly for this purpose, 

 and were respectively attached to the eye-piece and the object- 

 glass. By the other method, an accurately measured volume of 

 blood was mixed with an equally accurately measured volume 

 of diluting fluid, and a microscopic volume of this mixture was 

 employed for the counting of the corpuscles. Welkerf has 

 recently suggested certain modifications in Vierordt's method. 



Vierordt does not determine the volume of the blood-corpuscles 

 by direct measurements, but by a simple calculation, which is 

 perhaps scarcely exact enough. This calculation, as well as that 

 of the whole blood-analysis, depends essentially upon the circum- 

 stance that comparative analyses are made of the whipped blood, 

 rich and poor in corpuscles ; according to Vierordt, the blood is 

 rendered poor in corpuscles either by the filtration of the whipped 

 blood through paper, or by the addition of a definite quantity of 

 previously analysed serum. All persons familiar with the princi- 

 ples of mathematics will readily comprehend Vierordt's ingenious 

 method, although they must at the same time perceive that, for 



* Arch. f. physiol. Heilk. Bd. 11, S. 26-73, 327-332, 547-558, and 854-884. 

 f Fechnei'-sCentralbl. 1853. No. 12, S. 218-222. 



