1889.] MR. F. E. BEDDARD ON ^OLOSOMA 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 GrafiF("Zur Kennt- 

 niss der physiulogischen Function des Chlorophylls im Thierreich," 

 Zool. Anzeiger, 188-1, 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 influence which caused its precipitation is withdrawn by the death 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. AVhen the colouring- 



1 Wfien 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 iodme, the black reaction was produced, which lasted a very 

 much longer time than when the iiving worm was submitted to the action 

 of the same fluid. On treatment with alcohol, the black staining iramecliately 

 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 

 in supposing that this is the nature of the black stain) is a function of the living 

 cell. 



