278 



BLOOD AND BLOOD EXAMINATION 



reckon the absolute amount of hemoglobin in milligrams in 1 c.mm. of blood. 

 [It is essential to remember that percentage readings are very misleading when 

 applied to children, since their normal is about 75 per cent, of the normal of 

 adult men. Women's blood contains 10-15 per cent, less coloring matter than 

 men's. All hemoglobin instruments should be graduated in milligrams per 

 c.mm. of blood instead of in percentages of a supposed " normal." — Ed.] The 

 investigation is rather laborious because it can only be carried out with arti- 

 ficial illumination. The apparatus is quite expensive on account of the diffi- 

 culty in manufacturing the glass wedge. Its use, however, is valuable, for 

 an investigator in constant practice is able to reduce the errors to 5 per cent, 

 and less. 



The little apparatus of G-owers works on the following principle: A tube 

 contains a standard color solution which possesses the tint of a diluted watery 



Fig. 9. — Hemometek. (After v. Fleischl-Miescher.) 



hemoglobin solution. In a graduated glass tube of the same size a small but 

 accurately determined amount of blood is diluted with water until it is the 

 same color as the color in the test-tube; naturally this occurs the sooner the 

 thmner the blood is at the beginning. If, for example, an equalization of 

 color IS reached at 60, this indicates that the blood only contains 60 per cent, 

 of hemoglobin in comparison to normal blood. 



This test is quite simple and it may be completed in a few minutes during 

 the office hour ; the apparatus is very cheap. With a well made instrument 

 the errors may be reduced to from 10 to 5 per cent. I must call attention to 

 the fact that the manufacture of this apparatus is carried on by some quite 

 unreliable manufacturers, so that, for example, test solutions are furnished in 



