68 Sheppard, on Colour in Organised Substances. 
lion possesses. It happens, however, curiously enough, that 
in a subsequent conversation with Sorby, I learnt that a 
German naturalist has just lately discovered a monochromatic 
solution, ‘ the result of decaying algae,’ and of this Sorby 
promises to send me the particulars. 
“ Your solution, at all events, is new both to him and to 
English observers generally ; and we hope that your second 
visit to the scene of action will enable you to prepare a special 
communication for our next microscopical meeting. 
“ Believe, &c., 
“ J. 13. Reade.” 
A week after my first visit I again visited the spring for a 
farther supply of the film ; this, collected in bottles, was now 
properly cared for secundem artem , and great disappointment 
followed ; the velvet film remained olive brown, and the water 
remained colourless, save that now and then a vermilion 
deposit appeared capriciously, now here, now there, at the 
bottom of the containing dish. This vermilion behaved very 
oddly ; no sooner was a piece of the substance drawn to the 
surface than the colour, before intense red, quite disappeared, 
and more strangely when the vessel was shaken to diffuse the 
dye ; the colour all vanished, and instead of the water becom- 
ing red, the red became water. 
Of course the next step was to compare the circumstances 
of the first and second collections in order to ascertain why 
the former yielded spontaneously such a rich crop of results, 
whilst the latter remained barren, notwithstanding my care- 
ful husbandry. 
The circumstances differed in unimportant particulars ; 
the first specimen contained the ova already described, and 
was wrapped in paper impregnated by organic (animal) mat- 
ter ; the second was kept from contact with all foreign sub- 
stances — but not a single ovum, with its slimy envelope, could 
be found. Hoping to learn the law of the transformation of 
the w^ater into blood, I imitated, as nearly as I could, the 
circumstances of the first collection ; but neither india -rubber, 
ammonia, nor tobacco, was efficient to provoke the colour. I 
then tried glazed paper resembling that first used, but not, like 
it, greasy or strained. This produced a pale tinge of colour ; 
but, pale as it was, it was sufficient to indicate that there was 
a something in the mass which was capable of calling forth 
colour when it met with a suitable vehicle. 
I was proceeding to carry out experiments founded on this 
idea, when I saw an article in the ‘ Edinburgh Review’ for 
April discussing M. Pasteur’s book ‘ On Spontaneous Genera- 
