The adult organisation of Paragordius varius. 395 
flattened, wider than high, and without separating membranes (Hyp 
Figs. 22, 24, 25, Pl. 38; Figs. 37, 42, Pl. 39). The nuclei (Hyp. N) 
of the cuticular cells are the largest that occur in the hypodermis, 
generally rich in chromatin and with one true nucleolus; in the much 
flattened hypodermis of the sides of the trunk the nucleus also is 
flattened with its long axis parallel to the surface of the cuticle (sur- 
face views of such nuclei show them to be disc-shaped and more or 
less oval in outline, Sen.C Fig. 40, Pl. 39). The cytoplasm varies in 
structure from a dense, almost homogeneous appearance to a more or 
less vacuolar, and is sharply bounded from the cuticle showing that 
the latter does not continue to be produced during the mature 
existence. 
In the posterior region of the trunk, from about the region of 
the atrium backwards and most pronounced on the tail lobes, the 
cuticular cells have a different character, being longer and the cyto- 
plasm appearing striated (Hyp Figs. 41, Pl. 39; Figs. 71, 73, Pl. 41); 
here evidently the cuticular cells have preserved more of an em- 
bryonic character, and have become less modified and degenerate ; 
and here too the cuticle is thinner, and the process of cuticularisation 
apparently not completed. 
The gland cells (Gl. C Fig. 41, PL 39) are found most abundantly 
upon the outer surfaces of the tail lobes, and do not appear to ex- 
tend much forward of the plane of the atrium. They are narrower 
than the striated cuticular cells between which they lie, with a smaller 
rounded nucleus lying at about the middle. The following appearances 
of them may be interpreted as successive stage in the process of 
secretion of one kind of cell (Fig. 41): 1) the cell body without 
secretion, the cytoplasm clear and almost homogeneous so that the 
nucleus appears most distinctly; 2) a succession of stages where the 
secretion, which stains with haematoxylin, appears as smaller and 
larger globules within the cell body, gradually filling the cell and 
hiding the nucleus, terminating in a stage where one finds in the 
place of the cell an irregular, rod-like mass of deep staining secretion. 
These cells show no ducts or apertures passing into the fibrous layer 
of the cuticula, and since their secretion is not poured out between 
the hypodermis and the cuticle (there being indeed no space for it 
there), they probably have no functional value after the fibrous cuti- 
cula has been formed. And evidently even in the tail lobes, where 
the hypodermis has preserved more fully than elsewhere its original 
character, they are for the most part degenerate in character, an 
