266 



PROGRESS IN MICROSCOPY 



Where it is required to investigate another detail whose fluores- 

 cence spectrum is in the same plate, the measured density (^2) exhibits 

 the characteristic density d<i which may be compared direct with d^. 



When the fluorescence spectrum of a detail is to be drawn from 

 another plate, the comparison spectra are brought about under the 

 same conditions, the same source and the same rotatable sector. 

 Exposure-time is identical for both plates. Then the densities obtained 

 from the latter may be compared. 



As typical example of fluorescent microspectrophotometric measure- 

 ments. Fig. 10.22 shows, according to Sjostrand, the fluorescence of 

 the sciatic-nerve sheath of a rabbit. The ordinates show the densities d 



06 



0-4 



C2 



420 440 



480 



520 



560 



600 



640 



680 



Fig. 10.22. Spectral fluorescence of the sciatic-nerve sheath of a rabbit (after Sjostrand). 

 Solution of thiamine, solution of thiochrome. 



just defined. Figure 10.22 shows also the curves obtained with solu- 

 tions of thiochrome and thiamine, respectively. In this way, Sjostrand 

 found, in the sciatic-nerve sheath, the emission spectral line at 0-460 //, 

 characteristic of the triochrome. The spectrum also shows lines due 

 to thiamine derivates located in longer wave-length ranges. 



