THE MICROSCOPE. 



Vol. V. ANN ARBOE, DECEMBER, 1885. No. 12, 



ORIGINAL COMMUNICATIONS. 



A STUDY OF HUMAN BLOOD. 



C. H. STOWELL. 



IF a drop of blood be placed on the slide, the cover glass ap- 

 plied, and the preparation transferred to the microscope, the 

 examination is anything but satisfactory. The number of cor- 

 puscles in the field is so great and the number of layers so 

 many that the specimen cannot be studied to advantage. Again, 

 if mixtures are used to dilute the blood, unless prepared with 

 the greatest care, they will cause changes in the corpuscles. 

 "When but a comparatively short examination is required the 

 following method will be found satisfactory : To procure the 

 drop of blood, one of the fingers is congested by tying around 

 its base a string or handkerchief. When well filled with blood 

 a fine cambric needle is quickly thrust through the outer coats 

 of the skin over the end of the congested organ. One surface 

 of a glass slide is now gently breathed upon and a drop of blood 

 freshly pressed from the puncture, is brought in contact with 

 this slightly moistened surface. One surface of the cover glass 

 is now breathed upon and immediately its edge is placed close 

 to, just in contact with, the edge of the drop of blood. With 

 the aid of a needle the cover is lowered away from the drop, — 

 not over it,- — until it touches the slide. The blood corpuscles 

 will readily flow between these moist glasses, by capillary at- 

 traction, until the surface beneath the cover glass is nearly or 

 entirely covered. 



There is but one single layer of corpuscles and they show 

 to the best possible advantage. For this method to be success- 

 ful it should be carried out rapidly and the moisture should not 



