62 THE BACTERIA CNDEK PHYSICAL AGFACIES 



algae, &c. all of which are more concerned with alterations of chemical com- 

 position must be added the influence of sunlight in diminishing the number of 

 bacteria. A critical review of the most important labours and researches per- 

 formed in respect of the self-purification of rivers is given by E. DUCLAUX (V.). 

 All tln pathogenic Schizoinycete* seem to succumb under the influence of sun- 

 light. This has been shown by Arloingand Ward in respect of B-tcillux ((nth, -acts; 

 (aillard for 7>. tyf-hi ub'/cmilmilia ; Fansini for Vibrio cholera a^idt'.cn and a 



Fi<;. -2<). Thickly-sown plate culture of typing bacilli on sigar-a^ar. Covered with 

 paper letter- and exposed to the sun's rays for i }_, hours, ihcn kept twenty-four 

 hours in the dark, win- IT upon development of" thickly con-re-ateil whitish 

 colonies was found only at the parts covered by the letters. (Aj'hr //. ],<iclnnr.) 

 Nat. size. 



fungus giving rise to white pus in wounds (Sfaj>hylococcus j>ii</< m* 

 ( 'hiiiiliewski for the organism which induces the formation of yellow pus (XL 

 pi/ojenes aureius), and the bacillus of erysipelas (Streptococcus erysipelatis); JJob. 

 Koch for ttac'dlns tuberculosis; Charrin for the organism producing swine- 

 erysipelas ; and others. Most of the non-pathogenic fission fungi also succumb 

 to the influence of light. (1. \LKOTTI (I.) arranged a number of chromogenic 

 species in the following descending series, the first member of which ie>ists the 

 action of diffused daylight the longest: A''/r///</.? rubi-r, Micrococcns pro</i'/in*ns, 

 Sun-ilia rosea, Bacillus riolacens, B. pyocyaneus, B. lactis eri/throyenes. According 

 to the researches of GROTEXFELT (I.), the last named fi-sk.n fungus does not 

 produce red colouring matter at all when strongly illuminated. K. DUBOIS (I.) 

 ascertained that the luminous bacterium, Photobacterium sarcophilum, found on 



