65 
Sheppard, on Colour in Organised, Substances. 
midway we came to a clear spring rising in a rocky basin 
(Kentish rag, carbonate of lime), and on all the submerged 
stones in the basin there was a dark olive-brown coating, 
covering every surface with a velvet-like film, and thick 
enough to be scraped ofl* in an unbroken sheet — just such a 
coating, in fact, as promised oscillatorise and diatoms. 
My companions being archaeologists, and not microscopists, 
in deference to their tastes I had forborne to take any appa- 
ratus or receivers for collections, having on other occasions 
bored them by wasting time, as they thought, about pond- 
edges and spring-heads. Having no bottles, I begged from 
my friend a piece of paper — a part of the wrapper of his 
sandwiches — and to this piece of paper, greasy and glazed 
with some sort of size, is partly due the result which I am 
about to communicate. 
The specimen in the paper was placed in an india-rubber 
tobacco pouch, and remained undisturbed for twenty-four 
hours before I opened the parcel to separate a piece for mi- 
croscopical examination. As soon as the parcel was taken 
from the pouch, I noticed that the paper was stained here 
and there with hues of red, blue, and purple, and (the paper 
being removed) in the wet mass within I saw small clots of 
red jelly, exactly counterfeiting recently coagulated blood. 
I selected a clot and pat it on a slide, whilst the rest of the 
mass was laid in a glass of clear water. This mass consisted 
of interwoven oscillatorise and other confervoidese, with na- 
vicula-shaped diatoms pervading the texture, and, excepting 
the clots, presenting nothing that is not to be found on the 
stones of every wall. The specimen on the slide was remark- 
able. The colour, before placing the glass on the stage, was 
opaque red, looking like a small quantity of vermilion mixed 
with water ; but when held up to the light the red disap- 
peared, and a pale transparent blue took its place. 
Under the microscope (1 -inch, “ B”) the clot appeared of 
a pale blueish-grey, quite transparent and structureless ; but 
entangled in this now grey-looking jelly were several bodies 
which I took to be ova. In form they were pointed-oval — 
almost kite-shaped — buff as to colour, and moderately opaque. 
Each example contained a small collection of reddish and 
brownish cells, with one, or at most two, larger spherical, 
colourless globules — perhaps vacuoles. 
After examining two or three of the clots, and finding in 
each some of these ova, I concluded that in some manner 
they contributed to the formation of the red colour ; and from 
farther experience I feel certain that but for the dirty piece 
of paper and these bodies this interesting subject would never 
