1889.] MR. F. E. BEDDARD ON ZOLOSOMA TENEBRARUM. 53 
in question were really coloured by chlorophyll, I kept a number of 
individuals in the dark for a considerable period (14 days), but 
without any change being apparent in the green bodies. This is 
not, however, a conclusive argument, since von Graff (‘‘ Zur Kennt- 
niss der physivlogischen Function des Chlorophylls im Thierreich,”’ 
Zool. Anzeiger, 1884, p. 520) found that in Hydra kept in complete 
darkness for one hundred and nine days “ there was no alteration 
either in the form or in the colour”’ of the chlorophyll-corpuscles. 
Being unable to extract a sufficient quantity of the green pigment 
for spectroscopic investigation, I treated the living worm with solu- 
tion of iodine (both alcoholic and in iodide of potassium) and 
obtained a very remarkable reaction. 
The cells containing the green oil-drops are stained of a deep 
blue-black colour by iodine; the colour can be seen to gradually 
spread over the cell and to be limited to the peripheral protoplasm ; 
almost as soon as the colour is developed it rapidly disappears, 
leaving the protoplasm stained yellow. I found it impossible to 
retain the stain for more than a few moments. If the worm was 
first killed by acids, &c., this iodine reaction did not take place ; it 
is therefore evidently produced by the living protoplasm only. Al- 
though there is a certain resemblance here to the starch-reaction, 
the fact that the blue-black staining could not be produced after the 
death of the cells is against such an interpretation. I am inclined 
to think that the appearances described are produced by the depo- 
sition of elemental iodine, which is rapidly redissolved after the 
influence which caused its precipitation is withdrawn by the death 
of the cell’. 
I should be extremely glad if it could be found that the iodine 
reaction was characteristic of starch (or some carbo-hydrate), as I 
could then announce the formation of this body in cells coloured 
green by a substance that is not chlorophyll (I shall show this 
presently); this would be a very strong argument in favour of 
Pringsheim’s ‘‘ screen theory.” 
When the living worm was treated with various acids, the 
colouring-matter was dissolved out, often expelled with violence 
from the body ; in the latter case the oily vehicle of the colouring- 
matter took the form of a fine coiled thread, thicker at one end; 
there were all gradations in form between this and an oval; the same 
effects were produced by crushing the worm. When the colouring- 
1 When a living example of olosoma tenebrarum was treated with Stokes’s 
fluid, it was killed almost immediately, but no universal change of colour 
could be detected in the green bodies; when the worm was subsequently 
treated with iodine, the black reaction was produced, which lasted a very 
much longer time than when the living worm was submitted to the action 
of the same fluid. On treatment with alcohol, the black staining immediately 
vanished and the worm was decolorized. This seems to suggest that although 
the worm is killed by the treatment with Stokes’s fluid, the green cells are not 
at once killed by that reagent—not so rapidly as they are by solution of iodine; 
and also it seems to prove that the precipitation of the iodine (if I am right 
ee that this is the nature of the black stain) is a function of the living 
cell, 
