198 Prof. H. James-Clark on the Spongie ciliatee 
this time was what occurred at the rounded ends of the two 
half-separated bodies of the new pair of individuals. This was 
no more nor less than the incipient development of the flagel- 
lum, which proceeded in this wise :—At each of the rounded 
ends just mentioned a slight commotion appeared, resembling 
the molecular vibrations of a granule; ad then there arose 
quite rapidly a sharp and distinct filamentous outgrowth (jf), 
which kept itself in a constant state of narrow vibrations, or a 
sort of shivering. 
By 1.23 p.m. the newly born flagella (fig. 18, #7) had risen 
to half the height of the collar (4), and still remained in a 
shivering condition, whilst the body had divided almost to its 
base, and the collar had broadened to a widely terminating 
truncate cone. 
In about a minute more, the dividing process had risen into 
the collar and split it (fig. 19, e®) upwards for one-quarter of 
its height; and the still tremulous flagella (7) were slightly 
longer than in the last phase. 
By 1.26 p.m. the body was divided (fig. 20) to its posterior ter- 
mination, and the fissuration (e?) of the collar (6) had reached half- 
way to the distal edge, and was further sketched out as it were 
by two opposing shallow longitudinal furrows, which extended 
to the margin. At this period the collar was broader at the 
still undivided portion than below; so that on the whole it had 
a very wide campanuliform shape, or rather (since the divided 
portion was rolled inwards at the opposing edges) was like 
two slightly flaring, broad funnels, merged into each other at 
their broader ends. The flagella (7) also had developed con- 
siderably, and extended a short distance beyond the collar; 
and the front end of the body, from the middle of which the 
flagellum arises, had assumed the low, truncate, conical shape 
of the adult form. 
From this time onward the division did not appear to go 
forward so rapidly; and the new bodies seemed to be more 
particularly occupied in shaping themselves into the charac- 
teristic form of the adult. The collar, however, was not long 
in dividing itself up to its margin (fig. 21), but still the two 
cylindrical halves (6,6) did not separate at their extremes as 
soon as the fission reached that point. 
At 1.35 P.M. the self-division was completed (fig. 22), as far as 
the body proper was concerned, and had extended a short way 
down the pedicel (pd*). The margins of the two collars (0) 
seemed merely to lie in contact; and each collar had a slightly 
funnel-shaped outline, and was considerably more elevated in 
proportion to its diameter than in the adult form. The flagel- 
lum (ff) was nearly as long as that of the full-grown body, 
