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Walliclfls conclusion that the ectosarc gradually fades into the 
endosarc, and predisposes me to believe in their mutual con- 
vertibility. 
The question of an internal circulation stands in close 
relation to that of the nature of the two parts of the sarcode. 
Apart from the deceptive changes in the apparent position of 
the internal organs, arising from the constant variations in 
shape which the Amoeba undergoes, there is unquestionably a 
real movement in the interior of the endosarc. When the 
animal pushes out a lobe or pseudopodium, this sometimes 
consists only of a prolongation of the ectosarc (fig. 14), but in 
others the endosarc is also extended (fig. 1). In the latter case 
a rush of granules may be seen flowing in the direction of the 
new pseudopod, and we have already observed that contractile 
vesicles and food vacuoles move freely within the endosarc. All 
these circumstances prove that the endosarc possesses a much 
greater amount of fluidity than the ectosarc. Schultze believes 
that the movement of the granules is a true cyclosis, analogous 
to what takes place within the cells of Vallisneria, Chara, and 
other plants. But Dr. Wallich much more correctly regards 
it as a secondary and mechanical effect, consequent on the 
inherent vital contractility of the sarcode, which causes the 
particles to flow in the direction of the preponderating pseudo- 
podian projections. He cannot discover any return stream, 
which would be readily observable were it present. Extensi- 
bility and contractility are obvious attributes of the sarcode, 
at least when it has been in contact with external media suffi- 
ciently long to secure its due consolidation. 
Such are the ordinary features of the Amoeba, and it will be 
readily perceived how few materials they furnish on which to 
found specific distinctions. Such attempts have been made by 
several writers, who have relied upon variations in the size and 
number of the pseudopodian processes, differences of colour 
or fluidity; the presence or absence of small external villous 
appendages in the anal region ; vivacity or slowness of move- 
ments, and the presence or absence of crystalloids. But all 
these features are such as may merely represent different 
states of the same creature. Those who are familiar with the 
wide range of variation which all the lowest forms of animal 
and vegetable life exhibit, will be prepared to recognize similar 
phenomena in the Amoebae, and they will not be disappointed 
when they apply their general conclusions to the special study 
of the animals under consideration. Dr. Wallich has shown 
most clearly that all the varieties known by the names of 
radiosa, diffluens, globularis, Schultzii, limax, princeps, guttula, 
verrucosa, quadrilineata, actinophora, and villosa are but 
different states of one species, since in one locality he found 
