432 Ww. A. HASWELL. 
test; but there can be little doubt, from its appearance and 
behaviour in other respects, that it is composed of cellulose. 
The colour of the chromatophore, which occupies a large 
part of the interior, is somewhat variable. It is rarely grass- 
ereen, but always contains a brownish ingredient, and in 
some cases would be best described as brown with a tinge of 
green—the appearance presented closely resembling that of 
the chromatophores of Diatoms or Dinoflagellates. All the 
colouring matter is soluble in alcohol. 
‘The nucleus always occupies the same position, in amass of 
uncoloured protoplasm at the broader end of the cell. It 
contains a very regular chromatin network without nucleoli 
or other similar bodies. Towards the middle of the cell is a 
single spherical pyrenoid, very rarely a couple. 
A large proportion of the Accela seem to lodge 
biotic” Algz. In many cases these are bright green in 
colour, containing no other colouring matter than chlorophyll. 
ce sym- 
But in Haplodiscus, and in some species of Convoluta 
and Amphicherus, they are yellow or brown. Whether 
the presence of a cell-wall is a special feature of the 
Zooxanthella of the Australian form remains to be deter- 
mined. 
In the case of Convoluta, Gamble and Keeble (8) con- 
clude that the green cells are not of paramount importance 
in the nutrition of the worm, which freely ingests various 
organisms. In the Australian form there is still less need 
for any symbiotic nutrition, since recently-captured speci- 
mens are almost invariably found to contain relatively large 
animals—Rotifers, Polychzts, Crustacea, etc., in process of 
digestion. 
Further details with regard to these Algz are reserved 
for the present until more complete data have been obtained. 
Digestive System and Parenchyma.—As in most 
Aceela, a pharynx is absent. To apply the term, as von 
Graff, Pereyaslawzewa (22), and others do, to what is neither 
more nor less than an integumentary pit with the epidermal 
layer somewhat thickened, appears to me to be misleading. 
