1134 BIOLOGICAL EFFECTS OF RADIATION 



even if "protoplasmic" sensitivity were in this respect less variable. 

 Among those studies reporting comparative differences a few only will be 

 cited as examples, each in the order of increasing sensitivity: (Larsen, 93a) 

 B. typhi muris, B. coli commune, B, typhi, Staphylococcus pyogenes citreus, 

 B. prodigiosus, Staphylococcus pyogenes albus, Staphylococcus pyogenes 

 aureus, B. pyocyaneus, and B. cyanogenus (the first being killed in 60 

 min.,andthe last in 25 min.) ; (Bisceglie, 17) B. pyocyaneus, Staphylococcus 

 aureus, B. anthracis; (Ehrismann, 44a) B. diphtheriae, B. prodigiosus, 

 B. coli. Staphylococcus pyogenes aureus, Vibrio cholerae, and B. typhi. 



Bang (8c) found little difference between the tubercle bacillus and 

 Staphylococcus pyogenes aureus. Pothoff (123), using 12 species or strains 

 of bacteria in water suspensions, could detect no striking differences in 

 their relative resistance to radiation. Several strains of B. coli were killed 

 in about 2 min. Two of the forms of Staphylococcus pyogenes were killed in 

 30 sec, and one in 60 sec. One unnamed species was reported killed 

 in 15 sec. Among seven species studied by Bayne- Jones and Van der 

 Lingen (10), no significant differences in resistance were found. Like- 

 wise Gates (59) and Wyckoff (166) reported that the order of resistance 

 of Staphylococcus aureus and B. coli is much the same. Contrary to the 

 general evidence, Wiesner (160) assumes that there are bacteria (Luft- 

 keime) in nature accommodated to the strongest sunlight, and not ordi- 

 narily injured by the action of light. It was more or less characteristic 

 of that period to regard the animal parasitic and saprophytic bacteria as 

 likely to possess greater sensitivity toward light on the ground of habitat 

 adjustment, and Wiesner seems to accept this view. 



Ward (155), Arloing (4, 5), and others among the earlier students of 

 lethal light effects, observed that the spores of bacteria as well as vegeta- 

 tive stages are killed with suitable length of exposure, although some 

 confusion developed in respect to the comparative resistance of spores and 

 vegetative stages. Arloing (5) reported anthrax spores less resistant than 

 vegetative stages, while Jansen (82) in an extensive study declared that 

 the spores are about 5 to 7 times as resistant as the vegetative form of 

 bacteria in general. Pothoff (123) reported the extent of growth merely 

 by descriptive terms, showing that the vegetative form of anthrax gave 

 about the same amount of killing in 5 sec. as was obtained in 30 sec. with 

 spores. Using B. subtilis, at a concentration of 1/10,000, the vegetative 

 form was reduced to 5 colonies after an exposure of 45 sec, whereas 

 3 min. were required to reduce the spore stage to occasional colonies; with 

 B. mesentericus, spores were also more resistant, but the difference was less 

 striking. 



In some comparative experiments with plant viruses, Duggar and 

 Hollaender (42) exposed B. subtilis and B. megatherium to monochromatic 

 ultra-violet in a suspension containing physiological salt solution and 

 traces of bouillon and of the virus preparation. At a survival value of 



