portee: teichonympha. 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 mai'kiug the boundary 

 between the '•' head " and the " body " of the animal. It has tlie form 

 of a hemispherical bow], 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- 

 pare the position of the lines 21-21 and 23-23 in Fig. 15), this par- 

 tition gives rise to a kind of radiation, which seems to emanate from the 

 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 (bastoucelli) 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, nl.) is situated in the anterior or " liead " 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 iu hajmatoxyliu. 



