BUDS OF CEPHALODISCUS NIGRESCENS. 47 
the alimentary system (fig. 37, plate 5). A large testis extends as far as the extreme 
posterior end of the visceral mass, and may occasionally send-off a lateral branch 
which is lodged in the stolon. The duct at the anterior, pointed end of the testis 
differs from the corresponding duct of the ovary in having no red pigment, or at 
most a few specks of red. 
A transverse section of the, testis shows a moderately thick wall of uniform 
character throughout (except in the foremost portion or duct), composed of four or 
five layers of cells in various stages of spermatogenesis. The central cavity is 
occupied by large masses of spermatozoa. 
The openings of the ducts of both ovaries and testes lie at the bottom of shallow 
depressions, the epithelium of which is composed of taller and more closely set cells 
than those investing the greater part of the body. 
Buds and Budding. 
A bud in its earliest stages of development appears as a small clavate mass 
(fig. 60, plate 7), the free end of which gradually flattens out (fig. 61), and becomes 
differentiated from the “body.” The flattened terminal portion is of semicircular 
outline, and develops into the anterior part of the buccal shield. The red line of 
the buccal shield appears at about this stage, before the posterior edge of the shield 
is clearly outlined. The shield becomes broader and more sharply defined from 
the “body” (fig. 62), and grows at a much faster rate than the latter (figs. 63-65). 
Fig. 65 gives a side view of a bud of the same age as that represented in fig. 64, 
and serves to show the great mobility of the shield even at this early period of 
development. The posterior flap of the shield can be brought sharply forward, 
i.e. ventrally, and the “body” appears as an elongated pyriform structure projecting 
from the middle of the dorsal surface of the shield, and is continued back into the 
tapering stalk. 
Shortly after this stage is reached the plumes begin to develop, as small hemi- 
spherical projections situated dorsally to the middle of the shield, and arranged in 
a curved line that runs immediately anterior to the “body” (fig. 66). The plume- 
axes elongate and flatten into thick ovate discs, and the pinnules grow out from 
the edges. 
After this, the shield increases at a relatively slower rate, the body enlarges 
rapidly (fig. 67), and, in the later stages, the visceral mass begins to bulge 
posteriorly (fig. 68), so that the stalk is no longer terminal, but on the ventral 
side of the body. The plumes by this time have increased to the number of 
twelve or fourteen, and the line of their bases has gradually changed from a 
semicircle to almost a circle. 
As in C. dodecalophus, the shield of a young bud (with two pairs of plume- 
VOL. II, T 
