450 



FARR ET AL. 



Fig. 4. Whole brain section of case 8180 r stained to show the Nissl substance. The 

 neurons show tigrolysis only in the limits of the neoplasm. 



power magnification with the Nissl stain ) shows intact neurons as further 

 evidence of a lack of irradiation efTect. The cortical areas receiving maxi- 

 mum exposure received 1,905 rads from capture gamma. This is calculated 

 on the basis of the same set of assumptions as the previous values. 



Discussion 



In assessing the role of thermal neutrons as a potentially noxious agent 

 when administered to the central nervous system, certain assumptions are 

 iinplicit. Among these is the assumption that the only eflFect which need be 

 considered in the exposures of the size discussed is that which residts in a 

 gamma emission as a result of thermal neutron capture by tissue components. 



