44 



PRACTICAL PHYSIOLOGY. 



[VI. 



its floor divided into squares $ mm., in which the blood-corpuscles 

 are counted. 



(/.) The diluting solution consists of a solution of sodic sulphate 

 in distilled water sp. gr. 1025. 



2. Mode of Using the Instrument. 



(a.) By means of the pipette (A) place 995 c.mm. of the dilut- 

 ing solution in the mixing jar (D). 



(/;.) Puncture a finger near the root of the nail with the lancet 

 projecting from (F), and with the pipette (B) suck up 5 c.mm. of 



FIG. 20. Gowers' Hsemocytometer. A. Pipette for measuring the diluting solution ; B. 

 For measuring the blood ; C. Cell with divisions on the floor, mounted on a slide, to 

 which springs are fixed to secure the cover-glass ; D. Vessel in which the solution is 

 made ; E. Spud for mixing the blood and solution ; F. Guarded spear-pointed needle. 



the blood, and blow it into the diluting solution, and mix the two 

 with the stirrer (E). 



(c.) Place a drop of the mixture on the centre of the glass cell 

 (C), see that it exactly nils the cell, and cover it gently with the 

 cover-glass, securing the latter with the two springs. Place the 

 cell with its plate on the stage of a microscope, and focus for the 

 squares ruled on its base. 



(c.) When the corpuscles have subsided, count the number in 

 ten squares, and this, when multiplied by 10,000, gives the number 

 in a cubic millimetre of blood. 



