156 SIDNEY F. HARMER. 
Flustra papyrea. 
Some days after the beginning of the experiment, the leuco- 
cytes, as in other species, are found to be coloured by Bismarck- 
brown. Ina colony which had been treated first with indigo- 
carmine and afterwards with Bismarck-brown, the leucocytes, 
at the 188th hour, were either yellow or green (in the latter 
case obviously containing the two pigments), and contained, 
within their vacuoles, granules coloured by Bismarck-brown 
or by indigo-carmine, or by both substances. 
In one experiment it was noticed that the “lateral cords” 
of nearly all the individuals had the appearance shown in 
fig. 15, 213 hours after their first immersion in Bismarck- 
brown. The contents of the lateral cords appeared granular, 
but enclosed a number of round vacuoles of a yellow colour. 
This is probably to be interpreted as an excretory process. 
IV. SumMARY AND GENERAL CoNCLUSIONS. 
The experiments made with various artificial pigments 
showed conclusively that the tissues did not all react alike to 
these pigments, the absorption of which was, in each species, 
limited to certain definite tissues. As Kowalevsky has pointed 
out for other Invertebrates, the action was precisely the same 
if the animals were immersed in a solution of two pigments 
mixed. Thus, when indigo-carmine mixed with Bismarck- 
brown was used, the leucocytes were at first blue (although 
they subsequently absorbed Bismarck-brown from other tis- 
sues), just as if the former pigment had been used by itself. 
The results on the absorption of the pigments may be 
summarised as follows : 
Leucocytes.—These cells, in all the species examined, readily 
absorb indigo-carmine. Although they do not appear to take 
up Bismarck-brown directly, they abstract it from other tissues 
at a later period. They are not in the least affected by 
carmine in suspension, nor by carminate of ammonia. 
Alimentary Canal.—The pigmented granules of the stomach 
