THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL, 



Vol. X. OCTOBER, 1889. No. 10. 



All comimmicatiotis for this Journal, ivheiher relating to business or to editorial 

 matters, and all books, pamphlets, exchanges, etc., should be addressed to Ameri- 

 can Monthly Microscopical Jourtial, Box 6jo, Washington, D. C. 



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 Triibfter &~= Co., j/ Ludgate Hill, Londo7i, or to Mr. W. P. Collins, i^y Great 

 Portland street, London, accompanied by the yearly price of Jive shillings. 



Histological Technique of the Blood. 



By GEORGE C. FREEBORN, M. D., 



INSTRUCTOR IN NORMAL HISTOLOGV IN THE COLLEGE OF PHYSICIANS AND SURGEONS, N. Y. 



Fresh Blood. — To obtain human blood for examination, the finger 

 is wrapped around m a spiral manner with a piece of string from its 

 proximal to its distal end. This produces a congestion of the finger- 

 tip, and on making a slight puncture with a needle at the edge of the 

 nail a drop of blood will flow out. This is wiped oft' and the new 

 drop that appears is to be used. This is transferred quickly to the cen- 

 tre of a slide covered with a cover-glass and the edge of the cover 

 painted around with a ring of vaseline or oil to prevent evaporation. 



In animals (dog, cat, rabbit, etc.) the blood can be obtained from a 

 slight puncture made in one of the veins of the ear ; in the frog by 

 cutting oft' the tip of one of the toes, or by opening up the thorax and 

 cutting oft' the apex of the heart. The blood in the first method is 

 always mixed with more or less Jymph. 



For studying the changes in the red cells, due to the concentration 

 of the plasma by evaporation, the ring of vaseline or oil around the 

 cover-glass is omitted. Then, on examination near the edge of the 

 cover, the changes in the red cells will soon be seen. 



The application of fluid reagents is best made by the method of irri- 

 gation. A bit of filter-paper is brought in contact with one edge of 

 the cover-glass and a drop of the reagent with the edge on the opposite 

 side. As the fluid is sucked up by the filter-paper the reagent runs in 

 on the opposite side. Volatile reagents are applied in the following 

 manner : Place a drop of the reagent in the bottom of a cell on a slide 

 and invert a cover-glass containing a thin layer of blood over the cell. 



Explanation of Plate. 

 Fig. 1. Strieker's hot stage and gas chamber. Fig. 3. Malassez'.s blood-cell counter. 



Fig. 2. Hotain's mixer. Fig. 4. Field of Malassez's blood-cell counter. 



Copyright, 1889, by C. W. Smiley. 



