X-KAY MICROSCOPY 



Table 2. Linear Absorption Coefficients 

 (after table from Zuppinger) 



this table one may see that x-ray ab- 

 sorption comprises in muscle 2.62 X^, blood 

 2.61 X^ liver and spleen 2.61 X^ kidney 2.62 

 X^ ; in other words they have ec^ual or almost 

 equal absorption coefficients. Only hairs 

 (2.89 X3), thyroid and cartilage (2.70 X^), 

 placenta (2.75 X^) and especially nerves 

 (3.12 X^) possess more or less high coefficients 

 distinguishing them from other tissues. One 

 may find out from this table that some or- 

 gans cannot be differentiated one from an- 

 other in radiographs (for instance liver and 

 spleen, or muscle and kidney, etc.) ; the differ- 

 ence of absorption between some tissues is 

 so minute that they also have little chance 

 to be differentiated (e.g., muscle from liver 

 and spleen). The situation with absorption 

 improves considerably in microradiography 

 due to another factor of equation 8 — X^ If, 

 for instance, the difference in attenuation 



coefficients between carbon and oxygen is 

 0.802 for 1 A, this difference with 2.0 A 

 wavelength comprises 5.973, in other words 

 it increases about 7 times (110). However, 

 this possibility of improving the morpholog- 

 ical differentiation has its limits in medico- 

 biological research due to the very slight 

 penetrative power of ultra soft x-rays (see 

 above). 



From the study of all these data one may 

 conclude that the application of microra- 

 diography to the study of genuine (non- 

 contrasted) body tissues encounters many 

 difficulties which are partly unsurmountable 

 at this stage of development in microradio- 

 graphical technique. Only calcium-contain- 

 ing tissues possess an absorption coefficient 

 so high that they can be differentiated in all 

 their parts without the technique of coloring. 

 One has not to forget, however, that con- 



596 



