ACTION OF LIGHT ON MICRO-ORGANISMS 371 



these were then likewise transferred to the incubator. 

 It was found that in those flasks which had been in- 

 solated for 6 and 9 hours respectively, as well as in the 

 control flasks kept in the dark, abundant growths made 

 their appearance. In the flasks insolated during 12 

 hours the vegetation was more scanty ; whilst those 

 flasks which had been insolated during 16, 24, 27, 

 and 30 hours respectively remained entirely free from 

 growths. 



Momont, in order to investigate the effect of insola- 

 tion on anthrax spores in a moist condition, where 

 their vitality would not be interfered with by the 

 alteration in the medium during insolation, introduced 

 such spores into pure water. One such inoculated 

 drop of water was placed in a test-tube and insolated ; 

 it was found that 44 hours' exposure to direct sunshine 

 was sufficient to destroy the spores, whilst similar ex- 

 periments conducted in vacuum tubes revealed the fact 

 that, in the absence of air, anthrax spores in water 

 can withstand insolation for over 110 hours, and retain, 

 moreover, their virulence. 



Buchner l conducted a number of experiments on 

 the vitality of various organisms in distilled and ordinary 

 tap water during insolation. This investigator states 

 that on all the varieties of bacteria, typhoid bacilli, 

 B. coli communis, B. pyocyaneus, cholera bacilli, and 

 various putrefying bacteria, which he introduced into 

 and examined in water, light exercised a most markedly 

 deleterious effect. The following is the only experi- 

 ment quoted by this author : A water into which 

 about 100,000 germs per c.c. of B. coli communis had 

 been introduced at the commencement of the experi- 

 ment, after one -hour's exposure in direct sunlight con- 



1 ' Ueber den Einfluss des Lichtes auf Bakterien,' Centra Iblatt fur 

 BaTtteriologie, vol. xi., 1892, p. 781. 



B B 2 



