of the 'Trichodina pediculus (?). 971 
At three o’clock a similar character prevailed; two, however, 
of the vesicles having grown larger than the other two. 
At four o’clock the selfsame two larger ones had attained to 
double the size of the two others, and one of them execeded the 
rest, and appeared to contain in its interior two rounded green 
nuclei. The two smaller ones now hardly surpassed the rounded 
green granules spoken of (fig. 4). 
At five o’clock two large vesicles were visible, and one smaller 
one of about one-fourth their size. The nucleus could still be 
detected about the centre of the animalcule, by a delicate pellucid 
outline, encroached upon and partly concealed by the peripheries 
of the two developing cells of the mterior (fig. 5). 
About six o’clock the two large vesicles had further augmented 
in size, and occupied the greater part of the area of the entire 
animal. One of these had in or upon it the two small granular 
masses described. The outline of the origmal nucleus was still 
perceptible. 
The two growing cells had now nearly come into contact, and 
every minute hastened the apposition which presently occurred, 
and in about another half-hour the two vesicles had blended 
together, a constriction only indicating the previous line of sepa- 
ration. Rather to one side of this constriction, and engaged 
within the periphery of the coalesced cells, thus occupying ne: arly 
the centre of the animal, the outline of a third vesicle could be 
seen, probably the original nucleus. Again, on the side opposite 
to the last vesicle—on that, viz. in which the gap of the mouth 
was perceptible,—was another sac, overlying slightly the margin 
of the large constricted coalesced cell, at the point of constriction, 
and contaming granules in its interior (fig. 6). 
The original rotundity of the animalecule had become, to some 
extent, alre eady interfered with by the development of the con- 
tained cell; but this interference was destined to proceed ; for 
now the outer tunic began to protrude at one pole, in the long 
axis of the enlarging interior cell, that is, im the direction m 
which the latter exerted its outward pressure. This tendency of 
the animal to increase in one direction continued, and an oval, 
and afterwards a pyriform figure was attained. 
The two green masses, descr ibed in one of the now-coalesced 
cells, occupied a position at the projecting part of the animalcule, 
remaining distinct (fig. 7). 
The great cell would seem now to have undergone some de- 
gree of contraction on itself, for it became more globular, the 
constriction almost disappearing, and left a larger interval at the 
opposite end of the animal to that from which it protruded. In 
the meanwhile, the sac described as existing on the same side 
of the animalcule as the mouth, increased rapidly i in its dimen- 
sions, so much so as to compress the larger one, forming for 
