ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 573 



appear as luminous rings. He suggests a " Bakterienlampe " for use in 

 photography by bacterial light. Salt-pepton-gelatin is introduced into 

 a 1-2 litre Erlenmeyer flask, and inoculated before it has set with Micro- 

 coccus phosphor em. The flask is then rotated until its inner surface is 

 covered with a thin layer of the gelatin. After two days, numerous 

 colonies have developed which give out a beautiful blue-green light. 

 This living lamp lasts from two to three weeks at about 10° C, after 

 which its light diminishes. He finds that bacterial light has no power 

 to act on photographic plates through opaque bodies such as wood, but 

 that certain woods, cards, papers, etc., when laid on the sensitive surface 

 of a photographic plate can influence the subjacent layer quite inde- 

 pendently of any light. He has demonstrated thus, on a plate so treated 

 with a piece of wood and afterwards developed, the annual rings and 

 the distinction between wood and bark. 



Gum and By-products of Bacterium Sacchari.* — A. Greig Smith 

 has studied the slime produced by Bact. sacchari. He finds that in media 

 containing saccharose Bact. sacchari produces a galactan gum, carbon 

 dioxide, ethyl alcohol, lauric, palmitic, succinic, acetic and formic acids. 



Effect of certain Dyes upon the Cultural Characters of the 

 Bacillus typhosus and some other Micro-organisms.f — E. W.A.Walker 

 and W. Murray found that when the B. typhosus, the B. coli and the 

 cholera vibrio were grown on ordinary media containing a definite quan- 

 tity of Grubler's methyl-violet (C> B), ordinary gentian-violet, fuchsin, 

 methyl-green or methylene-blue, the cultural characters of these bacteria 

 underwent changes, consisting in the conversion of a normal short 

 bacillus into a form which presents itself as long filaments or threads,, 

 which may be twenty or more times the length of the ordinary bacillus. 

 These threads often showed no sign of segmentation, and sometimes 

 appeared truly branched. In the case of the Bacillus typhosus the long 

 forms when tested for the Gruber-Durham reaction rapidly agglutinated. 

 The best results were obtained by the addition of • 2 p.c. methyl-violet 

 to the culture medium. 



Role of Bacteria : Saprophytic and Pathogenic. f — E. Bodin, in 

 an important paper, considers the properties of bacteria. He arrives at 

 the following conclusions : That the property of being harmful to man 

 and to animals, termed virulence, is not an absolute quality of the 

 microbe. That this property can -become attenuated, or can even dis- 

 appear altogether in microbes originally highly pathogenic. That 

 inversely, certain conditions, among which are the becoming accustomed, 

 on the part of the microbe, to live in an animal medium, or, on the part 

 of the organism, disturbances in its defensive (phagocytic) function r 

 allow certain bacteria ordinarily innocuous to man and animals to be- 

 come virulent and pathogenic. The author therefore condemns the 

 classification of bacteria into the two groups of saprophytic and patho- 

 genic. He argues in favour of all infectious diseases being caused by 

 microbes at one time living in a state of saprophytism, instancing in 



* Proc. Linn. Soc. N.S.W., xxviii. (1903) pp. 834-8. 



t Brit. Med. Journ., 1904,11. pp. 16-8 (5 figs.). 



\ Travaux Scientiriques de rCniversite de Eennes, ii. (1903) pp. 409-42. 



