Keighley
July 6th. 1877
C. Darwin Esqre
Dear Sir
Many thanks for the account of Pouchet’s experiments1 the information is exactly what I wanted. I am not yet in a position to dispute his conclusions but I think I can prove a few more points beyond those which he mentions. My fish are the ordinary Gold Fish (Carp,2 in our mill ponds we breed large numbers a proportion are dark coloured placing these in a white vase with bright sunlight they become yellow. I have been led into this by finding that the introduction of a weed into one pond prevented the fish from changing to Golden or White the same fish in another pond; where the water is too hot for the weed to grow: are almost all Gold yellow or white.
If you have any interest in the experiments I shall be glad to inform you of their results.
I remain | Dear Sir | Yours ms truly | John Brigg—
I have two Alligators now about 3 feet long, which I keep in the mill ponds. I have good opportunity for noting their habits should you wish to know about them
Please cite as “DCP-LETT-11037,” in Ɛpsilon: The Charles Darwin Collection accessed on