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W. SCHOLZ, W. SCHLOTE AND W. HIRSCHBERGER 



Fig. 3. Plasmatic swelling and disorganization of the walls of two small \essels in 

 the white matter, still without effect on the neighboring tissue, 5 months after a single 

 dose of 2,000 r. van Gieson. 



No change of the neighboring myelin fibers can be demonstrated. These 

 changes occurred 5 months after the application of a single x-ray dose of 

 2,000 r. Within an area of spongy dissolution of the white matter in the 

 same case, plasmatic material with red blood corpuscles spreads out from 

 such vessels (Fig. 4). These conditions are demonstrated more distinctly 

 with the Mallory method in Fig. 5. The fibrinoid disorganization of the 

 vessel walls is here followed by erythrodiapedesis, hemorrhages, and fibrin- 

 containing fluid in the gray matter. In all places where the plasmatic fluid 

 spreads into the tissue, oxygen diff"usion is inhibited and the cellular ele- 

 ments become necrotic. 



On the whole, the findings in this second series confirm and complete the 

 results of our first investigation on x-ray changes in the spinal cord of adult 

 rabbits. The pathogenic mechanism seems the same as in the brains of 

 dogs, observed more than 20 years ago. We have not seen any proof for a 

 primary effect of ionizing radiation on the neuronal constituents of the tissue. 

 Whenever a damage of neuronal constituents could be observed, it was 

 accompanied and often preceded by changes in the barrier function. The 

 focal lesions of the white matter are distributed irregularly within the field 

 of x-irradiation of the cord. Some sections are filled with areas of demyelina- 

 tion, whereas at other levels not a single one can be seen. This may account 



