THE AMCEBA. 
195 
covered. This much is certain, that, however formed, whether 
within a capsule or not, the nuclei give birth to sarcoblasts, 
and we may now trace the further development of these 
bodies, as noticed by Dr. Wallich ; for though he was not able 
to watch that development whilst the bodies were inclosed 
within the Amoeba cyst, he had no difficulty in doing so, in the 
case of similar ones, which appeared identical with them, only 
floating free in the surrounding medium. It must be remem- 
bered that we are now about to speak of the changes that appear 
to affect two classes of objects, which have had a very different 
origin, viz., the free sarcoblasts derived from the aggregated 
granules of the sarcode during encystation, and those mulberry 
masses derived by some process or other from the broken-up 
nucleus. At first these sarcoblasts are densely granular, con- 
taining little of the fluid hyaline Protoplasm (fig. 6) ; the 
beginning of their further development is marked by an 
increase in this hyaline element, followed by the consolidation 
of the outer part of the sarcode, which now becomes differen- 
tiated into ectosarc and endosarc. But as yet, according to 
Dr. Wallich, there is no mutual conversion of the one into the 
other. We next find one or more contracting vesicles (fig. 7, c), 
making their appearance within the endosarc. These are 
at first exceedingly minute, but they gradually expand as 
the yet globular germ itself does, and at the same time the 
granular nucleus (fig. 7, n) also appears. The latter organ 
may have existed previously, but been obscured by the dense 
aggregation of the granules, whilst the separation or dilution 
of these granules attending the growth of the animal may have 
brought the organ into view. Up to this point no circula- 
tion of the granules occurs beyond the shifting of a few of 
them occasioned by the pressure of the growing contractile 
vesicle. “In short,” Dr. Wallich observes, “the organism 
consists essentially of a quiescent spherical globule of 
sarcode containing granules, a contractile vesecle, and a 
nucleus.” But a new phase of life now commences. 
The contractile vesicle having attained to its normal dimen- 
sions, moves to one side of the germ, where it causes a 
protrusion from the circular outline (fig. 8, c'), and where it 
ultimately bursts through the ectosarc, this being the first of 
those operations which will continue to take place so long as the 
animalcule retains its vigour. At the place where the capsule 
broke through the ectosarc there now exists a minute 
mamelliform projection. The same phenomenon is soon 
repeated ; the ectosarc having been Weakened by the rupture 
of the first vesicle, apparently prepares the way for the 
bursting of a second at the same point, where the outline of 
the organism becomes still more irregular (fig. 9, v ), and thus 
