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1878.] Ameba Proteus. 237 
this as represented by Rösel is of greater size than that given by 
Ehrenberg to A. princeps. It would naturally be supposed that 
an Ameba discovered by the earliest observers, with instruments 
less perfect than those later in use, would be one of the larger _ 
and more common forms. That such was the case appears 
fairly proved by both figures and descriptions. 
Rosel, referring to a figure of his little Proteus, remarks that in 
its natural size it looks like fig. A. Now this represents the ani- 
mal in its quiescent state, in globular form, and the figure measures 
four-fifths of a line. No Ameéa has since been recorded so large 
- as this, and we may look upon the figure as somewhat exag- 
gerated, which might readily have occurred without the accurate 
measuring instruments which came later into application to micro- 
scopic objects. Rdésel also refers to his having held the Proteus 
at rest with the point of a feather, so that the evidence is suffi- 
cient to prove that the Amada was one of the largest kind. 
Taking size alone into consideration, Résel’s Proteus is as far 
removed in one direction from Ehrenberg’s Amæba princeps, as 
Ameba diffuens is in the opposite direction. But in other char- 
acters Rosel’s Proteus agrees with the former closely, and not 
with the latter. 
Ehrenberg describes A. princeps as yellowish, the A. diffuens as 
colorless. Résel says nothing of the color of the Proteus, but 
his figures are colored yellowish. Most of Rosel’s figures exhibit 
the characteristic changes of form of the animal in movement, 
and of one of these he remarks that in its branching it resembles 
the antlers of the deer. 
As regards the concurrence of size and color of Résel’s Proteus, 
it might apply to other large Amæbeæ, instead of A. princeps, as 
for instance the A. villosa of Wallich, or the Pelomyxa palustris 
of Greef, but the changes of form represented as occurring in the 
Proteus of Résel, approach it rather to the former than to either 
of the latter. 
Miiller’s descriptions and figures of Proteus difluens, which that 
author regarded the same as Résel’s Proteus, likewise appear to 
apply to the same animal named A. princeps by Ehrenberg, rather 
_ than to that which he named A. difluens. 
If the views taken, as above expressed, are correct, it must be 
. admitted that the Ameba princeps of Ehrenberg is the same ani- 
mal as the Proteus diffiuens of Müller and the little Proteus of 
