Notes . 
487 
and the mixture then diluted with water and shaken, the ether 
separates and rises to the surface as a dark bluish green fluid, showing 
a red fluorescence, whilst the fluid beneath is colourless and contains 
a white flocculent residue. As the ether evaporates, a pinkish red dye 
which it also holds in solution, but which is masked by the green dye, 
is deposited in rings at the edges and on the sides of the tube or 
evaporating basin. If, instead of using ether, the separation of the 
green dye from the warmed alcoholic extract is effected by benzene, 
the fluid beneath remains a pinkish red, whilst the supernatant 
benzene is dark bluish green in colour, and shows a red fluorescence 
in reflected light. The alkali and acid methods 1 of extraction for 
alkachlorophyll and chlorophyllan yielded brownish fluids only. 
Both the benzene and the ether extracts, when exposed to light and 
in the presence of oxygen, rapidly become brown and fade. It is 
true that the material from which these extractions were made was 
not absolutely pure, microscopical examination before extraction 
showing the presence of occasional green organisms ; and even 
though these formed but a fraction of a percentage of the total 
mass, still for absolute certainty the extraction needs to be repeated 
with perfectly pure cultures, which, owing to the peculiar conditions 
under which B. photometricum develops, and the consequent extreme 
difficulty of isolating it, are by no means easy to obtain in sufficient 
quantity. Still as far as they go the facts above mentioned seem to 
indicate that a green dye apparently identical with chlorophyll may be 
extracted from B. photometricum, as well as a pinkish red one which 
is insoluble in benzene but soluble in ether, and in alcohol even when 
diluted largely with water. Engelmann 2 has shown that the point of 
maximal assimilation in B. photometricum corresponds with the point 
of maximal absorption, which curiously enough lies, as determined by 
his bolometer experiments, in the dark ultra-red rays. It appears, 
therefore, that B. photometricum resembles the Florideae in so far as 
the bacterio-purpurin which it contains is a compound assimilatory 
chromophyll, which when treated with hot alcohol splits up into two 
differently coloured substances, namely, chlorophyll and a pinkish 
red pigment which in colour and solubility shows a distinct resem- 
blance to the pinkish red pigment which may be extracted from 
red Algae. A. J. EWART. 
1 See Marchlewski, Chlorophyll and its Derivatives. 
2 Engelmann, Bot. Zeitg., Oct. 1888. 
