V COLOUR-PHENOMENA IN WORMS 113 
the characters of the pigments, there are some inter¬ 
esting facts connected with the pigmentation disclosed 
by a series of experiments made by Mr. Sidney F. 
Harmer. Mr. Harmer’s experiments were made with 
a view to determine the exact nature of the so-called 
“ brown bodies ” of marine Polyzoa, which have been 
supposed to be excretory. 
These brown bodies arise roughly in the following 
way. Each polypide in the colony is only capable 
of a relatively brief existence ; after a certain period 
the organs, and especially the alimentary canal, be¬ 
come degenerate and, fusing together into a mass, 
form the so-called brown body which is found lying 
inside the zooecium. The brown colour is due in 
large part to masses of dark pigment which occur in 
the cells of the alimentary canal. Contemporane¬ 
ously with the formation of the brown body there 
occurs in many forms a process of regeneration, 
which results in the formation of a polypide bud, 
and ultimately of a new individual. The brown 
body is either eliminated by means of the gut of the 
new polypide, or is simply stored up in the cavity of 
the zooecium. 
In studying these processes Harmer made a series 
of expeiiments with solutions of various pigments, 
such as indigo-carmine and Bismarck-brown. His 
method was briefly as follows :—living colonies were 
placed in sea-water containing the pigments in 
solution ; after a short time they were transferred to 
clean water and the distribution of the pigment in 
the different tissues carefully studied. The results 
obtained differed considerably according to the pig¬ 
ment employed, but in general terms it was found 
I 
