1882.] Action of Coloured Light on Carp. 351 
that is, to light and shade— or whether adtinic rays and the 
colour of the light have also an influence in producing the 
change, the following experiments were conduced. If they 
indicate nothing else, they certainly show that : — Firstly, 
colour is a fadtor in the change, as the blue produced darker 
fish than the black, and red had no adtion whatever. 
Secondly, that blue, the colour of the sky, and not black or 
green, the colour of mud and foliage, is the best and most 
healthy colour for carp. 
First Series. 
The globes intended for the reception of the carp were 
covered externally with a varnish coloured with aniline dyes. 
The dyes used were alkaline blue for the blue, eosine for the 
red, tropseoline for the yellow, and a mixture of aniline dye 
producing a grass green for the green. The black globes 
were varnished externally with Brunswick black, while in 
every case the tops were covered with large concave covers 
similarly coloured to the globes, air being freely admitted by 
the intervention of corks between the globe and cover. The 
carp used were the Prussian carp, Cyprinus gibelio. 
Red. 
Jan. 14 th . — Three normally coloured carp were put into 
three separate globes coloured with eosine. The fish were 
healthy. 
Jan. 2,1st . — All in good health and would feed. 
Feb. 10 th .- — The three fish were removed from their globes 
into an uncoloured one, and on comparison with carp which 
had been kept in uncoloured globes for the same length of 
time were pronounced by four persons, making independent 
observations, to be unchanged in colour. They were then 
replaced in the red globes. 
Yellow Light. 
Jan. i/[th . — Three normally coloured carp were put into 
three separate globes coloured with tropseoline. The fish 
were healthy. 
Jan. 21 st . — The fish were healthy, but paler. 
Feb. 10th .— The fish were considered, by four persons 
making independent observations, to be much paler than the 
normally coloured. 
Blue Light. 
Jan. 14 th . — Three normally coloured fish were placed in 
three separate globes. 
