SENSITIZATION TO HEAT DUE TO EXPOSURE TO LIGHT 

 OF SHORT WAVE-LENGTHS. 



By W. T. BOVIE and ALICE KLEIN. 



{From the Cancer Commission of Harvard University, Boston.) 



(Received for publication, October 25, 1918.) 



This paper is a report of some experiments on the effect of heat 

 upon organisms which have been exposed to fluorite rays. The ex- 

 periments have yielded valuable information concerning the mechan- 

 *ism of the action of rays. They show that the exposed organisms 

 (Paramecium caudatum) are made extremely sensitive to the influ- 

 ence of heat. 



The experiments are of interest because they show the necessity 

 of a careful control of the temperature of the radiated organisms 

 both during and after the radiation. Heretofore investigators have 

 paid but little, if any, attention to temperature control in their 

 radiation experiments. They have, perhaps, considered the matter 

 unimportant, since the rate of most photochemical reactions is in- 

 dependent of temperature. The effect of heat upon the organism 

 which has been made sensitive to heat by radiation must be clearly 

 distinguished from its effect upon the specific photochemical reaction, 

 for in the former case the effect is upon a series of reactions initiated 

 by the exposure and not upon the photochemical change itself. 



The heat sensitization resulting from radiation appears to be of 

 general occurrence. It has been found in Laminaria exposed to the 

 rays from radium emanation^ and in egg white exposed to the rays 

 from a quartz mercury-vapor lamp.^ In the case of the heat- 

 sensitized egg white visible coagulation occurs at a lower tempera- 

 ture than in the non-radiated control. The degree of sensitization 

 increases with the amount of radiation so that with sufficient expo- 



^ Unpublished experiments by the writer. 



^ Bovie, W. T., Temperature coefficient of the coagulation caused by ultra- 

 violet light, Science, 1913, xxxvii, 373. 



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