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ORVILLE T. BAILEY 



Fig. 5. Longitudinal section through posterior (.oluinns ol spinal cord to show 

 myelin sheath degeneration. Gallocyanin-van Gieson X250. Dosage 6,220 r Ta"" in 

 43/2 hours. Slight weakness of legs and loss of sphincter control 3 days after radiation: 

 gradual recovery over 10 weeks; monkey then normal 1 month; gradual onset of 

 paraparesis, persisting until sacrifice 9 months after radiation. Compare with Fig. 6. 



neuron disintegration, a finding in agreement with Reynolds (1946), who 

 compares this effect with that obtained with multilayer films of lecithin 

 radiated on a water surface. Doses as low as 600 r destroy the normal molecu- 

 lar arrangement. 



In embedded sections, this myelin degeneration appears as scattered vacu- 

 oles (Fig. 5), corresponding in distribution with droplets stained with oil 

 red O (Fig. 6). The areas which fail to take such stains for the demonstra- 

 tion of myelin as Weil's method are considerably larger than shown by the 

 other two techniques. Reasons for this difference are not clear. 



The nerve fibers themselves are interrupted by irregular zones of necrosis 

 affecting individual fibers (Fig. 7). Adjacent nerve fiber segments are 

 swollen or partially fragmented. While the distribution of such injured nerve 

 fibers corresponds closely to the area of radiation, it is possible with smaller 



