MEMORANDA. 283 
I will not take up your space further, as I intend to discuss 
the whole subject, which abounds with matter of the deepest 
importance to physiology and medicine, as critically as pos- 
sible in my lectures at the University, which recommence 
next week, when I hope also to show the presence of the 
poison of our Australian snakes in the blood of bitten and 
inoculated animals, and to make some experiments on the 
possibility of saying life—Grorcr B. Hatrorn, Australia. 
On the Action of Monads in producing Colouring Matter— 
Will you allow me to make a few remarks on Mr. Shep- 
pard’s paper on the action of monads in producing a colour- 
ing matter? It appears to me that a mystery has been here 
conjured up quite unnecessarily, and that, in searching for 
a hidden cause to explain the phenomenon of his coloured 
liquid, Mr. Sheppard has overlooked the simple and obvious 
one. The pool whence Mr. Sheppard obtained his colour- 
producing matter was, he states, formed by a clear spring, 
rising In a rocky basin; and the olive-brown growth which 
he collected was “just such a coating as promised Oscilla- 
torie.”” He also says, he observed with the microscope a 
filament of Batrachospermum (p. 69). Now, it is a well- 
known fact, that the Oscillariz and their allied forms contain 
very remarkable colouring matters when alive, and without 
any artificial addition of albuminous matters. These colour- 
ing matters are soluble in water, and when the plants or 
parts of them die (as they were made to do by Mr. Shep- 
pard’s treatment), the water in which they are placed be- 
comes stained with the colour. I have not the slightest 
doubt that Mr. Sheppard’s mysterious fluid is a solution of 
one of these colouring matters. ‘The colouring matters of 
the lower alge have been studied by both Kutzing and 
Nageli, but most recently by Cohn, an abstract of whose 
researches appears in your last issue (p. 209 of the Journal). 
The Rey. J. B. Reade (p. 68 of the Transactions), in a letter 
quoted by Mr. Sheppard, says that he learnt from Mr. Sorby, 
“that a German naturalist had just lately discovered a mono- 
chromatic solution, ‘ the result of decaying alge ;’”? and Mr. 
Sheppard gives reasons for supposing that his and the Ger- 
man’s colour are not the same. The fact, however, is, that 
Mr. Sorby referred to Cohn’s paper, to which I had drawn 
his attention ; and Mr. Reade must altogether have misunder- 
stood what was said. Cohn describes two colouring matters, 
both of which are fluorescent, and therefore, in a certain 
