Sheppard, on Colour in Organised Substances. 69 
tion.’ In the review I found that M. Pasteur stated that 
certain monads and vibrious (our liquid contains them) had 
the property of changing the colours of nitrogenous and some 
other substances brought into contact with them under favor- 
able conditions. 
Now, given the monads, what evidence have we already 
to confirm M. Pasteur’s opinion ; greasy paper with some 
kind of size ; sized paper, but without grease ; and the slimy 
envelope of the eggs which your own nitric acid on a single 
drop proved to be albuminous, all developed colour when 
either of the above-mentioned substances was brought into 
contact with the confer void mass. I should mention that on 
one occasion a filament of Batrachospermum seemed to supply 
the albuminous vehicle and the colour. 
On the 3rd of May, having found, as above described, that 
soluble albumen, or some similar organic substance, was 
necessary to the production of the colour, I placed some of 
the film of my second gathering in contact with white of egg 
diluted with a little water ; the ingredients, after remaining 
together for a night, developed a glassful of, as one might 
have believed, magenta dye, and the dye thus obtained has 
the peculiarities of the already exhibited solution ; it possesses 
the same epipolar property, throwing back from its surface 
all the red and yellow rays, and transmitting the blue and 
violet. 
The globular bottle, viewed by reflected light, looks like a 
ball of red carnelian, and the contained liquid seems totally 
opaque ; but, by transmitted light, it is transparent and 
brightly tinted of a blue and violet colour. 
I need only further remark that Ehrenberg Eidmann (who 
is quoted in the e Edinburgh ’) and Pasteur seem to have 
overlooked the most striking quality of the new organic dye- 
stuff, viz., its poly chromatism. 
Decaying algse, which have been mentioned as capable of 
staining water, cannot be considered the cause of the develop- 
ment of our colour, inasmuch as I find that the fresh-gathered 
ferment (as I may call it) is more active than the stale, and 
farther decay of the organic materials involves decay of the 
colour, so that, as soon as decomposition begins (five to seven 
days), this grows paler, and when it is complete the colouring 
agent is powerless, decay having produced only a dirty foetid 
liquid, white with floating flakes. 
Note . — The vile smell which belongs to the film is not the 
result of decomposition, it is most pungent at the moment of 
gathering, and even on the hill-side it is almost unbearable. 
