74 
V, the eiliated vestibulum into which both E and d’ open 
with 
ce. its ciliated epithelium. 
A. the cavity of the large duct, directly continuous with the 
vestibulum V. E 
e. its ciliated epithelium. 
aa. the folds in communication with the central cavity. 
g. the tissue on which the epithelium is applied. 
mt. the muscular tissue enclosing tubes, ducts and glands, and 
suspended by radial fibres to the body-wall. 
Fig. 53. One of the ciliated epithelial cells of the tube A (fig. 52). The cell 
is very thin-walled; the protoplasm apparently contracted to a 
very small space, the nucleus only faintly stained and situated 
in the lower half. 
g.54. Epithelium of the anterior portion of the ducts RR’ (fig. 46). 
nn. the nuclei of the multicellular epithelium superposed upon 
the external muscular investment (not represented in the fig.). 
e. the inner layer of ciliated cells by wich the cavity is lined. 
ss. spherules secreted. 
Fig. 55. The same, further backwards. 
n, as in fig. 54. 
e. the inner epithelium in which the secreted globules are smaller 
and much more numerous. 
ff. spherules secreted in the deeper layers. 
Fig. 56. Separate ova, more highly magnified. 
09 
A. Very young stage. 
B. Stage in which yolk spherules make their appearance. 
C. Furthest advanced stage, seen from above. 
ss. yolk spherules. 
v. germinal vesiele containing 
U "min: P » 
gg’. double germinal spot and moreover 
l. an accessory body strongly staining with piero carmine. 
Fig. 57. Spherules secreted in the renal organ. 
a. when enclosed in vacuoles. 
b. when set free in the inner cavity. 
Fig.58. The vesicular body with cellular walls in the immediate vieinity of 
the heart /reconstructed from longitudinal sections). 
Fig.59. One of the lentieular bodies found in the vestibulum V (fig. 52) more 
or less resembling a prostate-corpuscle of higher animals (size 
6318): 
