NUMBER OF BLOOD-CORPUSCLES. 5 



number, copious draughts of water reduce it; during inanition the 

 number is relatively increased, because the blood plasma undergoes 

 decomposition sooner than the blood-corpuscles themselves (Buntzen). 

 The blood of the newly-born child contains a considerably larger number 

 of red corpuscles than the blood of the mother (Panum), while Hayem 

 found that the number diminished after the fourth day. In persons of 

 robust constitution the number is larger than in the weakly, and those 

 who live in the country have more than those who live in town. 



(The pathological conditions which affect the number of corpuscles . 

 are given at p. 22). 



a. Malasse^s Method of Estimating the number of Blood-Corpuscles. The 

 pointed end of a glass pipette (Fig. 2, A), the mixer, is dipped into the blood, and 

 by sucking the elastic tube, /, blood is drawn into the tube until it reaches the 

 mark, 4> on the stem of the pipette, or until the mark, 1, is reached. The 

 carefully-cleaned point of the pipette is dipped into the artificial serum, and this 

 is sucked into the pipette until it reaches the mark, 101. The artificial serum 

 consists of 1 vol. of solution of gum arabic (S. G. 1,020) and 3 vols. of a solution 

 of equal parts of sodic sulphate and sodic chloride (S. G. 1,020). The process of 

 mixing the two fluids is aided by the presence of a little glass ball (a) in the bulb 

 of the pipette. If blood is sucked up to the mark, |, the strength of the mixture 

 is 1:200; if to the mark, 1, it is 1:100. A small drop of the mixture is 

 allowed to run into the artificial capillary tube (c c) (the first portions are not 

 used in order to obtain a uniform sample from the bulb of the pipette). The 

 mixture passes by capillarity into the capillary tube, which, when full, is emptied 

 by blowing through the thin caoutchouc tube, /", and then again rilled to , 

 and the mixture sucked into the middle of the capillary tube. The capillary tube 

 is firmly fixed to a glass slide (B) with Canada balsam, and on it is inscribed the 

 following numbers : 



Length. Volume. 



600 yu . 89 



500 M . . . . 107 



400 M . . . . 134 



i.e., a length of the capillary tube of GOO, 500, and 400 M contains - a) 1 | r , -5-^, 

 cubic millimetre. 



In order to count the corpuscles, the same combination of lenses must always be 

 used. Select Hartnack's objective, No. 5 (Nachet, No. 2) ; the ocular contains a 

 piece of glass divided into 100 squares. The tube of the microscope must be so 

 made that it can be pulled out and in. A micrometer, divided into -^fa milli- 

 metre, is placed upon the stage of the microscope : 1 division, therefore, 10 M 

 (p = i-,^ millimetre). The tube is now pulled out until the outer lines of the 

 divided ocular (tt, ii) exactly cover 600, 500, or 400 ;*. (500 M = k mm - i 3 most 

 convenient). A mark is made on the tube of the microscope to indicate how far 

 it must be drawn out to accomplish this object, and, having been made, it indicates, 

 once for all, how far the tube must be drawn out to indicate exactly 500 M. The 

 capillary tube is then filled and placed on the stage, instead of the micrometer, 

 when a picture like C is obtained. The length of the capillary tube, from tt to i i, 

 is 500 ju. All the corpuscles observable between t t and i i are now counted. 

 Suppose 315 corpuscles to be counted between 1 1 and i i, the number, 315, is then 

 multiplied by 107 (which stands opposite 500 on B) and also by 100 (when the 

 mixture of blood and serum was 1 : 100), or by 200 as the case may be i.e., 



