330 



Dr. S. Judd Lewis. 



of the past. The " absorption curve " is plotted therefore with extinction 

 coefficients as ordinates and wave-lengths as abscissa?. 



Absorption Spectra of Blood Sera. 



As no investigation of the ultra-violet absorption spectrum of blood serum 

 appears to have been made hitherto, it is desirable, first of all, to study the 

 absorption curve of normal serum in detail. 



— , 1 1 



ULTRA VIOLET ABSORPTION 



i . 



— 



1 



CURVE OF BLOOD SERUM 



a! 



1 





1 \ £ 











— I 1 1 i 1 L 



-fOOO 3500 3000 2500 ZOCO 



Wave -Zenyt/is 



The varying intensity of the absorption is expressed in the curve shown 

 in the figure. For purposes of reference it is convenient to describe the 

 several well characterised parts of the curve as " sections," and to designate 

 them by the letters of the Greek alphabet. The first section, «, coincides 

 with the visible region of the spectrum. The next section, /S, covers the 

 region of least extinction, extending from the borders of the visible to a 

 wave-length of about 3100, where it meets the foot of the steep ascent from 

 this point to the head of the band at about 2800, section 7. The descent 



