ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 101 



track is little affected, but over the surface development takes place 

 copiously, vibrio a spreading in a dirty whitish-yellow layer, beneath 

 which the agar mass for a depth of 1-2 mm. is clouded. Vibrio fi 

 produces a similar crust, but the underlay is dry, and it is impossible 

 to remove a specimen without taking up also the agar substance. On 

 potato both kinds thrive well. Vibrio a forms in two days a luxuriant 

 slimy layer of a yellow-red colour, which gradually darkens to chocolate. 

 Vibrio /? produces a thin dirty brownish-green overlay, which is removed 

 for examination with difficulty. The potatoes breeding vibrio a develope 

 a strong ammoniacal odour, but with vibrio /3 this occurs but slightly 

 or not at all. Both stain well with anilin dyes, especially with gentian- 

 violet. In hanging drops both varieties show lively movements. 



Phosphorescent Bacteria from Sea-water.* — Dr. O. Katz has 

 isolated three groups of micro-organisms, which are capable of cultiva- 

 tion in various nutrient media, and which by transference to marine 

 animals (fish, crustaceans) and to sea-water produce phosphorescence. 



(1) Bacillus smaragdino-plwspihorescens, obtained from dead marine 

 fish, is a short thick rod about 1 fx wide and about double as long 

 as wide. The ends are rounded off. It is not motile or flagellated. 

 When stained with anilins the peripheral parts only are dyed, a central 

 spot or " vacuole " remaining uncoloured. It grows in small colonies 

 on gelatin without liquefying the medium. It developes best at a tem- 

 perature of 20° C. or a little higher, and then emits a "wonderful 

 emerald-green" light. Grown at 13-15° C. development is slower and 

 the light is less intense. 



(2) Bacillus argenteo-phosphorescens was obtained from sea-water at 

 Elizabeth Bay, Sydney. On gelatin, after having been mixed with ten 

 drops of sea-water, there would appear, among a considerable number of 

 other colonies, not more than two of these luminous colonies. It is a 

 slender rod, tapering at the extremities and commonly slightly curved. 

 It is about 2 • 5 ^ long, and about three times as long as broad. It is 

 motile, but forms no filament. The best stains were anilin-fuchsin and 

 anilin-gentian-violet. The colonies do not liquefy gelatin, but spread 

 over it more than those of number 1. It grows best between 14° and 

 23° C, and within this range shows the greatest luminosity. The 

 emitted light is of a mild silvery appearance. 



(3) Bacillus cyano-phosphorescens was obtained from sea-water at 

 Little Bay, Sydney. It is a straight rod about 2*6 /jl long, and about 

 2^ times as long as broad. The ends are rounded off. It is motile, and 

 is often found as diplo-bacillus, but not often in chains. These are 

 commonly bent, attaining here and there a considerable length. It 

 stains well with alkaline methylin-blue, but a small central portion 

 remains uncoloured. It grows rather slowly in and upon gelatin, which 

 is gradually liquefied by it. It developes better on agar, where after a 

 comparatively short time it forms a substantial greyish-white sticky 

 layer. The optimum of growth and luminosity lies between 20° and 

 30° C, but a lower temperature is not unfavourable. The colour of the 

 light emitted has a decidedly bluish tint. The intensity lies between 

 those of I. and II. The author proposes to publish further details later. 



In some further remarks on the phosphorescent bacteria,f Dr. Katz 

 describes three additional kinds. 



* Proc. Linn. Soc. N. S. Wales, ii. (1887) pp. 331-6. 

 t Abstr. Proc. Linn. Soc. N. S. Wales, 1887, p. v. 



