XXXVI 

 EFFECTS OF RADIATION ON BACTERIA 



B. M. DUGGAR 



University of Wisconsin, Madison 



Sunlight. Ultra-violet radiation. Visible light. Influence of conditions on the 

 effectiveness of radiation. Absorption of radiant energy. Relative sensitivity. X-ray 

 radiation. Miscellaneous considerations. References. 



Quantitative investigations on the influence of radiation on bacteria 

 are relatively recent, though it would probably be unfortunate to name a 

 paper or date that might be regarded as a starting point for this type of 

 study. This difficulty is causally related to the fact that acceptable 

 accuracy in such studies involves so many factors of both biological and 

 physicochemical nature that no one investigator could at once rise above 

 the imperfections of technique as pertaining broadly to material, environ- 

 ment, or apparatus and thus be placed beyond criticism in the light of 

 later developments. The history of this field of work is, therefore, 

 not unlike that of many other fields in the fact that development has 

 been largely gradual, dependent upon advances in the basic sciences 

 and upon increasing knowledge of the behavior of organisms. At the 

 outset, however, recognition should be accorded the growing importance 

 of microorganisms, especially bacteria, as objects of study in fundamental 

 investigations in which ordinarily control of environment, purification 

 of the material, purity of stock, magnitude of population, practical 

 limitations in size and cost of apparatus, and comparative ease in securing 

 results statistically accurate are all among the essential factors. 



Observations on bacterial response to radiation extend back to 1877. 

 It would seem to be of interest and of importance to refer to some of the 

 developments resulting from the earlier studies as well as from the later, 

 but the extent of the literature renders a complete account impracticable. 

 An overwhelming majority of the papers deals with the bactericidal or 

 lethal effects. However, the bacteria also lend themselves for experi- 

 mental work on the influence of radiation on "stimulation," respiration, 

 products of metabolism, and many other physiological processes. Prac- 

 tical lines of work have developed in the direction of sanitation and 

 disinfection or sterilization. Available review articles on the effects of 

 radiation on bacteria are of limited scope. Among the helpful sum- 

 maries are the following: Bie (16), Busck (24), Duclaux (41), Ehrismann 

 and Noethling (45), Furniss (52), Hausmann (72), Janowski (81), 



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