CHAP. II.] 



THE BLOOD. 



75 



with a little solution of gum upon a slide, and the whole is allowed 

 to dry. The preparation is covered with a micrometer divided into 

 squares, and the corpuscles in the several squares can then be successively 

 counted 1 ." 



Method of In this case, as in all other methods, the blood, which is 



Malassez 2 . generally obtained by pricking the finger, is mixed with a 



known volume of a suitable solution. This is effected by means of the little 

 pipette A, which is specially constructed for the purpose; the longer 

 portion of the tube through which fluid is sucked is of capillary diameter 

 and bears the mark 1 near the bulb. 



On the shorter tube of the pipette, to which an indiarubber tube 

 is attached for facilitating aspiration, is marked the letter C. The bulb 

 of the pipette contains a glass bead. 



Blood is now drawn into the pipette to the mark 1, then a solution 

 of sodium sulphate or Potain's solution is aspirated until it reaches the 

 level of C ; the blood and its diluent are then mixed by agitating 

 the pipette, the bead facilitating the process. The mixture is next 

 introduced into a flattened capillary tube which is connected to a glass 

 slide (B) and which has been accurately calibrated so as to determine the 

 cubic capacity of various lengths of the tube in fractions of a cubic milli- 

 metre. The results of the calibration are engraved on the glass slide. Thus in 



A. 



B. 



FIG. 12. MALASSEZ' APPARATUS FOB THE ENUMERATION OF BLOOD CORPUSCLES. 



A. Pipette in which blood is measured and diluted (Melangeur). 



B. Flattened capillary tube fixed to slide, and calibrated. 



1 Strieker's Human and Comparative Histology, Art. "Blood," by Eollett, Vol. i. 

 p. 383 ; see also for a description of Vierordt's original method, Gscheidlen's Physio- 

 logische Methodik, p. 378. 



2 Malassez, " De la numeration des globules rouges du sang chez les mammiferes, 

 les oiseaux et les poissons." Comptes Rendus des Seances de VAcad. des Sciences. 

 2 Decembre, 1872. 



