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THE JOURNAL OF PHARMACOLOGY 



to read our level, as capillary attraction does not give us a sharp cross- 

 section. 



We next determine if the amount of hemoglobin is diminished, for this 

 purpose we have many instruments, one of the best being Fleischers hemo- 

 meter. It is constructed so that a known dilution of normal blood will 

 exactly correspond in color with 100 per cent, upon a sliding scale of ruby 

 glass, which passes between the diluted blood and the light. A diminu- 

 tion in amount of hemoglobin gives a lighter color to the solution, which 

 will be found to correspond with a lower percentage upon the scale. 



Technique, — Each of the small capillary tubes which accompany the 

 instrument has a capacity of about six and one-half cubic millimeters. By 

 placing the end of one of these tubes horizontally in a drop of blood, the 

 tube is filled by capillary attraction. We now partially fill one of the 

 chambers with distilled water and dissolve out the blood in tube. Next 

 fill both chambers with distilled water, and in a darkened room, with 

 candle light, we reflect light from the white reflector through the cham- 

 bers. By means of the thumbscrew we slide the ruby glass under the 

 chamber containing water until the two chambers both have the same 

 shade of color. Now read the figures on the scale. These figures do not 

 represent the percentage of hemoglobin in the blood, but merely the per- 

 centage in accordance with. this instrument, which is constructed so that 

 with five million red blood corpuscles the scale will show 100 per cent., 

 and, naturally, with a less number the scale would show diminution of 

 hemoglobin; therefore when we find diminution of hemoglobin we must 

 know the number of red blond corpuscles, so as to ascertain if this diminu- 

 tion is due to a diminution of corpuscles, or to a diminution of hemoglobin 

 in the individual corpuscles, or due to both factors. We express this 

 much better by what is termed color-index, or the amount of hemoglobin 

 per red blood corpuscle. 



examples: 



(1) Number of red blood corpuscles three million. Fleischel shows 30 

 per cent. What is the color index? 



If 5,000,000 red blood corpuscles should show Fleischel 100$ 

 Then 3,000,000 red blood corpuscles should show Fleischel 60$ 

 And 60$ Fleischel would have color-index 1 



Therefore 30$ Fleischel would have color-index .5 — a case of chlo- 

 rosis. 



(2) Number of red blood corpuscles 1,200,000. Fleischel 48$. Color- 



index? 

 If 5,000,000 red blood corpuscles should show Fleischel 100$ 



Then 1,200,000 red blood corpuscles should show Fleischel 24$ 

 And 21$ Fleischel would have color-index 1 



