COLOUR PHYSIOLOGY IN ANIMALS. 3849 
Colour Physiology in Animals.—Report of the Committee, consisting 
of Professor Hickson (Chairman), Dr. F. W. GAMBLE (Secretary), 
Dr. W. E. Hoye, and Dr. F. KEEBLE, appointed to enable 
Drs. Gamble and Keeble to conduct Researches on the relation 
between Respiratory Phenomena and Colour Changes in Animals. 
Durine the summer of 1906 Drs. Gamble and Keeble, working at 
Trégastel, Brittany, completed their joint investigation of the green cells 
-in the worm Convoluta roscoffensis. A full account of the results of this 
research has appeared in the ‘Quart. Journ. Micros. Science’ (vol. li., 
May 1907, pp. 167-219, pls. xiii. and xiv). In this paper the structure 
and life-history of the zoochlorelle, the changes which these bodies 
undergo within Convoluta, and the physiological significance of this 
association are dealt with at length. The authors conclude that this 
green cell or infecting organism is a probably new species of Chlamydo- 
monad alga exhibiting more primitive features than those of its nearest 
ally, the fresh-water genus Carteria. It is not only able to utilise for its 
metabolism such organic nitrogen compounds as urea and uric acid, but, 
thrives better in such solutions than in the presence of nitrates only. 
It is capable of a saprophytic as well as of a holophytic mode of life, and 
under the former conditions exists in both colourless and green forms. 
The association of this plastic infecting organism with Convoluta 
roscoffensis is traced by the authors to its hunger for organic nitrogen, 
such as is afforded by the egg-capsules of the worm and by the tissues of 
the young Convoluta. Inthe absence of the infecting organism Convoluta 
soon after hatching ceases to ingest protophytes and to grow. In the 
presence of this organism Convoluta becomes more translucent and grows 
rapidly. The excretory organs (protonephridia) so characteristic of other 
Turbellaria are here absent, and the authors conclude that the green 
cells function as an excretory system in Convoluta. 
The fission-products of the green cells that are first ingested by the 
young Convoluia become mere assimilative corpuscles. Their nucleus 
degenerates, their membrane disappears. They furnish the carbohydrate 
required by the animal tissues in a soluble form. Gradually the animal 
becomes parasitic upon them, and in the subsequent struggle on the part 
of both animal and plant to obtain sufficient nitrogen the green corpuscles 
are ingested by the phagocytes. 
An extension of this investigation to other cases of ‘symbiosis’ has 
been carried out during the past year. An allied form, the brown 
Convoluta paradoxa, was bred in fair numbers, and it was shown, contrary 
to the statements of von Graff, that the pigmented corpuscles of the egg 
do not give rise to infection of the young animal. Infection by a brown 
cell occurred sporadically in a few animals hatched from clutches of eggs 
laid in unfiltered sea-water to which alge were added. Efforts to isolate 
and cultivate this brown organism were, however, begun too late to give 
a successful result. 
This report concludes the joint work of Dr. Gamble and Dr. Keeble. 
The investigations on the xanthelle or chlorelle of Actinians, of Hydra, 
and of other Turbellaria than Convoluta, as well as the research on the 
pigment cells of Crustacea, are now being investigated by these authors 
working separately. For this reason the Committee do not ask to be 
reappointed. 
