4 MICROSCOPIC EXAMINATION OF THE BLOOD. 



If the total amount of blood in a man be taken at 4,400 cubic centimetres, the 

 corpuscles therein contained have a surface of 2,816 square metres, which is equal 

 to a square surface with a side of 80 paces ; 176 cubic centimetres of blood pass 

 through the lungs in a second, and the blood-corpuscles in this amount of blood 

 have a superficies of 81 square metres, equal to a square surface with a side of 13 

 paces (Welcker). 



(c.) Weight. The weight of a blood-corpuscle, according to Welcker, 

 is 0*00008 milligrammes. 



(d.) Number. According to Vierordt, the number exceeds 5,000,000 

 per cubic millimetre in the male, and 4.500,000 in the female ; so that, 

 in 10 Ibs. of blood, there are 25 billions of corpuscles. 



The venous blood of the small cutaneous veins contains more red 

 corpuscles than arterial blood. As a general rule, the number is in 

 inverse ratio to the amount of plasma ; hence, the number must vary 

 with the state of contraction of the blood-vessels, the pressure-diffusion 

 currents, and other conditions. The use of solid food increases their 



Fig. 2. 



Apparatus of Malassez for estimating the number of blood-corpuscles. A, the 

 mtlangeur, or pipette, for mixing the blood with the artificial serum. /, tube 

 for sucking up these fluids. B, the artificial capillary tube, with an elastic 

 tube, /, attached for filling it. C, appearance of B under the microscope 

 when it is filled with blood. The squares are due to a piece of glass divided 

 into squares, which is put in the ocular of the microscope. 



