HEMOGLOBIN 



279 



color tints such as thin watery blood solutions never show. Probably because 



of these poor instruments, there has been a partial opposition to the use of the 



Gowers apparatus. 



A short time ago Sahli made a change in the Gowers hemoglobinometer 



which appears to have added greatly to the value of the apparatus. For this 



purpose the measured quan- 

 tity of blood is first placed 

 in a slightly diluted hydro- 

 chloric acid solution which 

 produces a dark brown so- 

 lution of hydrochlorate of 



Fig. 10. — Hemometek. (After SahU.) 



Fig. 11. — Hemometer. (After Sahli.) 



hematin. This mixture is then diluted with water until it corresponds ex- 

 actly in color to a test solution which is furnished with the apparatus, which 

 also consists of hydrochlorate of hematin in a definite dilution. From the 

 amount of water necessary to produce this correspondence in color, we may 

 estimate the amount of hemoglobin in the drop of blood that has been 

 tested. In its mechanism the apparatus is much superior to the original, 

 as may be seen in the two illustrations which are placed side by side (Figs. 

 10 and 11). 



Among other instruments (of which there is a great number, each investi- 

 gator having his favorite one) I should like to mention one of the latest, the 

 practical importance of which upon a large scale must still be proven, and the 

 use of which is somoM^hat more difficult than of those previously depicted ; the 

 principle, however, is interesting, and differs greatly from that of the colorime- 

 tric ones that have been described ; for this reason it is necessary to compare its 

 results with those obtained by the aid of other instruments. I refer to the 

 hemophoto graph of Gaertner (see Figs. 12 and 13). Gaertner started from 

 the observation that the permeability of a diluted watery blood solution for the 

 photographic rays of sunlight was in inverse proportion to its hemoglobin con- 

 tent. For this reason he spreads the blood solution to be examined in a layer 

 of definite and uniform thickness, lays photographic paper under it, and per- 



