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J. STEPHENSON. 
are partly, the deeper are wholly, surrounded by the soft 
white masses of the cells (c 3 , c 3 ). The “ blood-glands ” 
appear as masses of grape-like follicles in segment YI, 
clustering round the backward prolongations of the muscle 
bands ; follicles also occur, as seen in sections, within the 
lobular aggregations of the chromopliil cells, both in seg- 
ment Y and on the pharynx. 
The Chromopliil Cells (PL 19, figs. 3, 4). The cells 
resemble, on the whole, those described for P. posthuma; 
but those of the posterior portion of the mass are in general 
more definite in outline than in the previous species, and do 
not here dissolve into the intercellular and connecting 
substance to the same extent. The nucleus is again cha- 
racteristic, — a spherical or shortly ovoid vesicle with large 
nucleolus and scattered chromatin. 
Transformation of the Cells. — In the backwardly 
projecting lobular masses of pharyngeal cells are strands 
of connective tissue, — a lightly-staining substance, scarcely 
definitely fibrillar in structure, though with an obvious longi- 
tudinal differentiation which is manifested by the deeper 
staining of small streaks in the direction of the length of 
the strand. In these strands are contained numerous cells, 
of the general nature of those already described ; many of 
these dissolve at their extremities into the substance of the 
strand without any demarcation ; some however are dis- 
tinctly outlined; the nuclei may still be perfectly distinct 
when most of the cytoplasm has dissolved away. Indefinite 
masses of deeper staining material, continuous with the 
substance of the strands, and without nuclei, are also seen 
(possibly nuclei are not present merely because of the plane 
in which the section happens to be taken). (Compare PI. 19, 
fig. 5, from P. liawayana). 
Similarly amongst the muscular fibres on the dorsum of 
the pharynx are strands of connective-tissue of the above 
type with small islets of cells. The cells are in part indi- 
vidually distinct, in part continuous with the connective- 
tissue. As the transformation of the cells proceeds, the 
