B 



Plate 1. Effect of an intraperitoneal injection of 5-hydroxytryptamine (0-5x10-^ mole) 

 administered 5 minutes preceding local irradiation of skin with soft X-rays (30 kV, H.V.D. 

 in tissue 2 mm. field size 2-5 cm diameter circle, dose 4000 r at skin surface) 



A. Right tlank of animal 20 days after irradiation (without protective agent) 

 B. Left flank of same animal 20 days after irradiation following 5-h\-drox>tryptamine 



treatment 



To face page 1 72 



