ANATOMICAL ELEMENTS. 



9 



The blood to be examined is diluted with ninety-nine parts of a liquid com- 

 posed of one volume of a solution of gum-arabic of a specific gravity of 1020 

 with three volumes of a solution of equal parts of sodium sulphate and of so- 

 dium chloride, also of a specific gravity of 1020. The mixture, containing one 

 part of blood in one hundred, is introduced into a small thermometer-tube 

 with an elliptical bore, the sides of the tube being ground flat for convenience 

 of microscopical examination. The 

 capacity of the tube is to be calcu- 

 lated by estimating the weight of a 

 volume of mercury contained in a 

 given length. The tube is then filled 

 with the diluted blood, and the num- 

 ber of corpuscles in a given length of 

 the tube is counted by means of a mi- 

 croscope fitted with an eye-piece mi- 

 crometer. In this way, the number 

 of corpuscles in a given volume of 

 blood can be readily estimated. In 

 man, the number in a cubic millime- 



tre of blood a millimetre = about 

 -fa of an inch is estimated to be be- 

 tween four and a half and five mill- 

 ions. 



FIG. 4. Artificial capillary, filled with a sanguin- 

 eous mixture, seen under a quadrilateral mi- 

 crometer (Malassez). 



According to the observations of Malassez, the proportion of corpuscles is 

 about the same in all parts of the arterial system. In the veins, the cor- 

 puscles are more abundant than in the arteries. In the venous system, the 

 blood of the splenic veins presents the largest proportion of corpuscles, and 



the proportion is smallest in the 

 blood of the hepatic veins. These 

 results favor the idea that the red 

 corpuscles are formed, to a certain 

 extent, in the spleen and that some 

 are destroyed in the liver ; but far- 

 ther observations are necessary to 

 render this view certain. 



Post-mortem Changes in the 

 Blood- Corpuscles. In examining 

 the fresh blood under the micro- 

 scope, after the specimen has been 

 under observation a short time, the 

 corpuscles are observed to assume a 

 peculiar appearance, from the de- 



FIG. 5. Human blood-corpuscles, showing post-mor- 

 tem alterations (Funke). 



velopment, on their surface, of very 

 minute, rounded projections, like 

 the granules of a raspberry. A little later, when they have become partly 

 desiccated, they present a shrunken appearance and their edges are more or 



