SCIENTIFIC PROCEEDINGS. 



Abstracts of Communications. 



Fifty-fourth meeting. 



Zoological Laboratory, Columbia University, May 21, 191 3. 

 President Ewing in the chair. 



98 (794) 



The color index and color of the red blood corpuscles. 

 By E. E. Butterfield. 



[From the Rockefeller Institute for Medical Research.] 



The present study is based largely on material observed several 

 years ago in Munich in the clinic of Prof. Friedrich Miiller. 

 The object of the study was to determine by means of exact 

 methods, (1) the existence of a high color index in pernicious 

 anemia, (2) the magnitude of the elevation of the color index, 

 and (3) the explanation of the phenomenon. 



The calibration of the pipette and the dimensions of the count- 

 ing chamber used for the erythrocyte counts were checked by 

 special methods. The hemoglobin determinations were made 

 spectrophotometrically (spectrophotometer of Konig, Martens 

 and Griinbaum, Nernst filament as light source). The manner 

 in which the hemoglobin concentration may be calculated from a 

 measurement of the light absorption follows from the equation for 

 the diminution in the intensity of homogeneous light on traversing 

 a planparallel layer of a colored solution : 



I' = Ie~ kU , (1) 



in which / = initial intensity, I' = final intensity, k — a constant, 

 / = linear thickness of the absorbing layer, and c = the concentra- 

 tion of the colored substance. I'll can be measured with spectro- 



155 



