150 



THE PHYSICS OF VIRUSES 



2400 2500 2600 2700 28002900- 

 Wavelength 



(a) 



2200 2400 2600 2800 3000/^ 

 Wavelength 



Fig. 6.2. (a) Absorption spectra of thymine and cytosine taken by Sins- 

 heimer, Scott, and Loof bourow (1950) showing the sharpening observed at low 

 temperatures, (b) Absorption spectra, taken by Holiday (1936), of trypto- 

 phane I and II and tyrosine III and IV in A^/lOHCl and A^/lONaOH, re- 

 spectively, showing the shift in character due to the shift in acidic or basic 

 character of these substances, (c) Absorption spectra of anthracene and an- 

 thraldehyde, taken by Jones (1947), showing the removal of modes of ab- 

 sorption by the introduction of the aldehyde group. 



