90 



Applied Biophysics 



No. 

 12 



13 



17 



18 



23 



24 



Dose in r 

 50 



50-100 



400 



500 



Biological Response 



30% inactivation of enzyme in dilute solution 

 icf. No. 28)21 



Tube-side of fluorescent screen during examina- 

 tion of patient (see No. 8)^2 



Temporary sterilization of ovary in women ^^^ 



Cessation of ovulation ^6 



Increases by 1% sex-linked lethal mutation in 

 Drosopiiila (maximum yield 15% with 5,150 r, 

 above which dose sperm degenerates) 1^5 



Initial injury to ovarian follicles and germinal 

 epithelium of domestic fowl ^"* 



Developmental abnormalities nearly 100% in frog 

 (see No. 9)5"^ 



Follicular disintegration in domestic fowl 34 



Mean lethal dose for Ascaris eggs ^^ 



Average skin-erythema dose for gamma rays 108 



Total destruction of male gonads of domestic 

 fowl 34 



Total destruction of female gonads of domestic 

 fowl 34 



Prevents "take" when inoculating benzpyrene- 

 induced sarcoma in rat ^^ 



Inhibits regeneration in worm-segments ^32, 140 



Delays cleavage in sea-urchin egg ^^* 



Causes complete inactivation of frog-sperm ^"^ 



30% inactivation of enzyme in concentrated solu- 

 tion (X 345 that of No. 12) 21 



Immediate death of chick-fibroblast cultures ^23 



Mean lethal dose B. mesentericus spores "^^ 



Mean lethal dose Colpidiuni colpoda 14, 15 



Inactivation of plant viruses ^^ 



These considerations illustrate some of the complexities of the 

 irradiation problem where organized body tissues are concerned. 

 Great technical advances have been made on the physical side 

 in delivering a given dose to a selected volume of tissue, but a 

 stage has been reached when it is easier to deliver a given dose 

 of radiation than to know precisely what biological changes that 

 irradiation produces in the tissue irradiated. It is time now 

 for corresponding advances on the biological side. 



2,000 



7,000 



