supporting lamella

528 W. B. HARDY.
ingested by the apical cells, both in the body of the animal and
in the proximal region of the blastostyles.
Towards the close of digestion a few free cells appear in
the somatic fluid. Each is rounded and composed of darkstaining
protoplasm embedding a nucleus with contained
nucleolus.
Before turning to the further fate of the food, that is to say
before considering the process of absorption, it will be well to
describe more particularly the contents and characters of the
vacuolate cells.
These when unloaded with nutritive spheres present the
appearance shown in fig. 18, where the cell is seen to consist
of a thin pellicle of protoplasm surrounding a large central
vacuole and embedding a nucleus. The protoplasm stains only
slightly. The outline of the cell is exceedingly sharply defined
by some staining material which has almost the appearance of a
cuticle. The process of loading with nutritive spheres is remarkable,
and essentially similar to that described by Miss Greenwood
as occurring in Hydra. The protoplasm at one point
develops a small vacuole which increases in size, and bulges into
the large vacuole. In this the nutritive sphere is formed from
the turbid semi-fluid material which first fills it. This process
continues until the whole of the cell becomes occupied by small
vacuoles, each containing a nutritive sphere. The size of the
cell, therefore, does not necessarily vary according to the amount
of reserve nutriment it contains. This, however, only holds
good for the vacuolate cells of the body. In the blastostyles
they are slightly different. In the first place the large central
vacuole is not developed, with the consequence that when the
cell discharges its nutritive spheres it frequently shrinks to the
condition of a cell with dense, non-vacuolated protoplasm, which
stains deeply with picro-carmine. In fig. 22, at 1 is a cell
without nutritive spheres, and at 2 one partly filled with
vacuoles containing nutritive spheres.
But the discharge of the nutritive spheres does not always
leave the cells smaller and solid. The vacuoles may persist
(fig. 22, 4), and the result is a remarkable cell with bubbly