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in Haliphysema. All these naturalists hold more or less strongly the 
same view as the brothers Hertwig. 
The last of this long series of researches is that of Hamann,* who 
has investigated the similar structures which occur in the oral region 
of many Ehizostome Medusae. While adopting the view of Cien- 
kowski as to the parasitic nature of the yellow cells of Kadiolarians, 
he maintains that those of anemones and jelly-fishes give quite 
different chemical reactions, and are to he regarded as unicellular 
glands. 
In the hope of clearing up these contradictions, I returned to 
Naples in October last, and first convinced myself of the accuracy 
of the observations of Cienkowski and Brandt as to the survival of 
the yellow cells in the bodies of dead Kadiolarians, and their assump- 
tion of the encysted amoeboid states. Their mode of division is 
thoroughly algoid ; just as in rapidly dividing Protococcus one finds 
not unfrequently groups of three and four. Starch is invariably 
present in notable quantity, as described by Haeckel ; the cell- wall 
is of true plant cellulose, and yields a magnificent blue with iodine 
and sulphuric acid, while the yellow colouring matter is identical 
with that of diatoms, and yields the same greenish residue after 
treatment with alcohol. So, too, in Velella , in sea-anemones, and in 
a Ehizostome medusa {Cassiopeia borbonica) in all cases the proto- 
plasm and nucleus, the cellulose, starch, and chlorophyll, can be made 
out in the most perfectly distinct way. The failures of former 
observers in obtaining these reactions (in which I at first also 
shared) have been simply due to neglect of the ordinary botanical 
precautions.! Such reactions will not succeed until the animal 
tissue has been preserved in alcohol, and macerated for some hours 
in a weak solution of caustic potash. Then, after neutralising the 
alkali by means of dilute acetic acid, and adding a weak solution of 
iodine, followed by strong sulphuric acid, the presence of starch and 
cellulose can be successively demonstrated in the same preparation. 
Thus, then, the chemical composition, as well as the structure and 
mode of division of these yellow cells are those of unicellular algse. 
I therefore propose for this alga the generic name of Pliilozoon , 
and distinguish four species, differing slightly in size, tint, mode 
* “ Die Mundarme d. Rhizostomen,” Jena Zeitschr ., 1881. 
f Pfeffer, “ Pflanzenphysiologie, ” Bd. I. p. 196. 
