PORTER: TRICHONYMPHA. 55 
a coarser and a finer. The coarsely granular protoplasm is situated 
chiefly in the anterior portion of the bell (Fig. 7, pr’pl.), but it is also 
continued backward along the surface, and likewise forms a pendant-like 
structure in the axis of the bell (pr’pl. ax., Figs. 7, 13, 15). It stains 
a little darker than the finer protoplasm which occupies the rest of the 
bell, but the transition between the two kinds is not very abrupt. 
Extending backward from the lip of the bell is a coarsely granular 
protoplasmic partition (Fig. 7, st. gran.), continuous with the coarsely 
granular protoplasm of the surface of the bell, and marking the boundary 
between the “ head” and the “body ” of the animal. It has the form 
of a hemispherical bowl, at or near the bottom of which is situated the 
nucleus. Although I have been unable to discover in connection with 
this granular partition the existence of any fine membrane serving to 
completely separate head and body, yet the constant relation of the 
nucleus to this granular layer proves the latter to be substantially a 
permanent boundary between these two regions of the animal. In cross 
sections of the animal in the region of the nucleus (Figs. 21, 23; com- 
15), this par- 
tition gives rise to a kind of radiation, which seems to emanate from the 
pare the position of the lines 21-21 and 23-23 in Fig. 
nucleus. This appearance might be produced if the bowl-shaped layer 
of granulations were corrugated or thrown into radiating folds; but I 
believe it is due instead to a regular alternation in the thickness of 
radiating portions of the bowl. As seen in cross sections (Figs. 21, 23) 
this bears a slight resemblance to the crown of rods (bastoncelli) figured 
and described by Grassi (’85, p. 236, Figs. 1, 2, 6), as nearly enveloping 
the nucleus in the case of Joenia annectens; but the fact that the bas- 
toncelli have a more precise form, being short club-shaped and curved, 
as well as the fact of their not being limited to a single zone, seems 
to me to preclude the possibility that these two structures are homol- 
ogous. 
The nucleus (Fig. 7, al.) is situated in the anterior or “head” por- 
tion of the animal, a little posterior to the constriction at the surface 
which marks the transition from the “bell” to the “body.” It lies 
wholly within the bell-shaped portion, however, and is generally sur- 
rounded by a thin sharply defined nuclear membrane. I have almost 
invariably found the chromatin broken up into chromosomes of varying 
size and shape, and without definite arrangement. 
Very frequently the nucleus is invested with an immensely thickened 
membrane (Plate 2, Fig. 22). This nuclear envelope consists of a clear 
homogeneous substance, which stains in eosin, but not in hematoxylin, 
