IX 
THE COLOURS OF INVERTEBRATES 
*95 
one waged over the question whether lobsters are 
black or red ! They find that, altogether apart from 
the famous Marennes oysters, there occurs in diseased 
oysters a green colour due to the presence of a large 
amount of copper. Drs. Boyce and Herdman do 
not believe that the large increase in the amount 
of copper normally present is necessarily the result 
of the presence of copper in the food, but “are 
inclined to suggest that it may be due to a disturbed 
metabolism, whereby the normal copper of the haemo- 
cyanin, which is probably passing through the body 
in minute amounts, ceases to be removed, and so 
becomes stored up in certain cells.” There is every 
reason to believe that such “green oysters” are 
highly poisonous, while the Marennes oysters are of 
course quite harmless. The paper thus settles a 
time-honoured controversy in the most satisfactory 
manner. 
Characters of the Coloration of 
Invertebrates 
With the Mollusca we end our study of the colours 
and colouring-matters of the Invertebrates. As a 
whole the Invertebrates are characterised by the 
number and diversity of their pigments, which in the 
simple forms occur in connection with internal organs 
and are often very variable ; by the frequent beauty of 
their structural colours ; and in the case of the more 
differentiated forms in certain groups, by the beauty 
of their patterns and markings. In Vertebrates the 
pigments are less numerous, often less vivid, and the 
beauty is usually due either to structural colour or 
