VI.] 



THE COLOURED BLOOD CORPUSCLES. 



43 



28. The Centrifugal Machine. -Precipitates or very minute particles 

 suspended in a fluid, e.g., blood- 

 corpuscles in serum may be readily 

 separated by this apparatus. 



The liquid is placed in strong glass 

 tubes, and these are in turn placed 

 in metallic cases, which can move on 

 a horizontal axis, the cases themselves 

 being placed in a horizontal disc 

 which is driven at the rate of 1000 

 revolutions per minute ; this causes 

 the tubes to take a horizontal posi- 

 tion, and after 30-40-60 minutes 

 rotation the precipitate or other sus- 

 pended particles are found at the 

 outer end of the tube. The serum 

 can thus be obtained perfectly 

 corpuscleless. 



There are various forms of this 

 apparatus. Some can be driven by 

 the hand and yield small quantities 

 of fluid, such as those sold by 

 Muencke of Berlin (see Stirling's 

 Outlines of Practical Histology, p. 94, 

 2 Ed. 1 893) or that made by Watson FIG. i 9 .-Method of Incinerating a Deposit to 

 & Laidlaw of Glasgow. When large Obtain the Ash. 



quantities of fluid are required, that 



made by Fr. Runne of Basel is one of the best. It requires a water or 

 gas-motor to drive it. At the present time Runiie's "Werkstatte f. prac. 

 Hechanik " are situated in Heidelberg. 



LESSON YI. 



THE COLOURED BLOOD CORPUSCLES. 

 SPECTRA OF HAEMOGLOBIN AND ITS COMPOUNDS. 



Enumeration of the Corpuscles. Several forms of instruments 

 are in use, e.g., those of Malassez, Zeiss, Bizzozero. and Gowers. 



1. The Hsemocytometer of Gowers (fig. 20) can be used with 

 any microscope, and consists of 



(a.) A small pipette, which, when fillet to the mark on its stem, 

 holds 995 c.mm. (tig. 20, A). 



(6.) A capillary tube to hold 5 c.mm, (B). 



(e.) A small glass jar in which the blood is diluted (D). 



(d.) A glass stirring rod (E). 



(e.) Fixed to a brass plate a cell i of a millimetre deep, and with 



