334 REMARKS ON PHOSPHORESCENT BACTERIA FROM SEA-WATER, 



This kind is represented by straight rods, measuring about 

 •002-6 mm. in length, and being about 2^ times as long 

 as broad. They are rounded off at their extremities; they 

 show spontaneous movements, and are often found as diplo- 

 bacillus, not so often in chains. These are commonly bent, 

 attaining here and there a considerable length. With alkaline 

 methylene-blue they stain fairly well, but a small central portion of 

 them remains unstained. Yet this appearance is not so striking 

 as in Bacillus smaragdino-jjhosphorescens, which shows the differen- 

 tiation between a well-coloured peripheral and an uncoloured inner 

 part in a very characteristic manner. 



Bacillus cyaneo-phos})horescens grows rather slowly on and in 

 nutritive gelatine which gradually becomes liquefied by it. In 

 this regard it differs widely from the two other kinds which, as 

 mentioned, cause no liquefaction of the gelatine. It thrives far 

 better on nutrient agar-agar, where after a comparatively short 

 time, it forms a substantia], greyish-white, sticky layer. 



The optimum of growth as well as of luminousness for this 

 microbe is between 20° C. and 30° C. ; a temperature fluctuating 

 between 13° and 15° C, however, does not seem at all unfavour- 

 able to its propagation or deleterious to its power of luminosity, 

 although higher temperatures as above intensify both growth and 

 phosphorescence. The colour of the light emitted in the dark or 

 at least in sufiiciently dark surroundings is of a decidedly bluish 

 tint, and seems to stand, as regards its degree, between those of 

 Bacillus No. I. and No. II. 



Comparing Dr. Fischer's description of the West Indian Bacillus 

 p)hosphorescens with what I have already ascertained about the 

 bacillus from Little Bay, I am almost inclined to consider these 

 two organisms as identical. However, I hesitate to pronounce a 

 definite opinion until I have made a larger number of individual 

 observations. 



In giving, as has been done above, a few preliminary remarks 

 on these three kinds of light-producing bacteria from sea-water — a 



