196 Prof. H. James-Clark on the Spongie ciliate: 
24, 24), and frequently much longer; but in the latter case it 
was sometimes observed to arise from the falling away of one 
of the resultants immediately after self-division occurred. It 
has a uniform thickness, or occasionally the slightest possible 
taper, from base to apex, and appears to be solid and homo- 
geneous in texture. It is apparently inflexible, and, even when 
carrying a single body, is united to it at a sharp angle with 
the longer axis of the latter (fig. 24). ie | 
Fissigemmation.—This is the only process of reproduction 
which has been observed. Several instances of this kind were 
partially followed through in an incidental way, and two com- 
plete courses were carefully noted and drawn within a half- 
hour of each other. The set of figures 13, 15, 17, 19, 21 relate 
to one individual, and figures 11, 12, 14, 16, 18, 20, 22 
to another belonging to the same colony. The rate of pro- 
gress of the former when the drawings were made was not 
noted; but that of the latter set was observed in four out of 
six of the intervals which occurred between the phases which 
the figures represent ; and during the progressive steps of the 
latter it was carefully recorded which of the successive stages 
of the former filled the intervals between those of the latter ; 
so that it can be said, in the strictest sense, that all the figures 
of both sets of observations represent the phases which were 
distinctly marked in the second series. In this way the fullest 
illustration possible was obtained, and no point was left unex- 
plained. ‘The whole time occupied by the process in the se- 
cond series was forty minutes. It has already been mentioned, 
when describing the form of the collar, that it assumes a 
bulging campanulate outline (fig. 11,6) as a preparatory, pre- 
liminary act in fissigemmation. In addition to this, it should 
be stated that it widens inordinately at the distal end, so as to 
exceed by one-third its normal breadth; but before it finally 
settles itself into this shape and proportions, it contracts and 
expands its diameter by a peculiar sort of vibrating motion, 
and passes through a series of changes of form which vary 
from a funnel-shape to a narrower cylindrical outline, or from 
either of these to a broader cylindrical proportion,—such, for 
instance, as figures 9 and 10 (representing the same individual) 
exemplify. This would appear, also, to be the time when the 
contractile vesicles divide; for at no other period were they 
observed to be more than two in number, as they are repre- 
sented in figs. 9 and 10 (cv). 
Immediately after this preparatory sign was discovered (the 
time being noted at 12.55 P.Mm.), the flagellum became unusu- 
ally conspicuous and much thicker, and moreover it lost its 
sigmoid flexure and assumed a perfectly straight carriage, with 
