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548 THE AMERICAN NATURALIST. [Vor. XXXIV. 
The number, shape, and size of the nuclei have already been 
alluded to. The chromatin granules are extremely numerous, 
especially abundant just within the nuclear membrane. They 
also form a densely crowded large mass in the center of the 
nucleus. Between the peripheral layer and central mass, the 
nucleoplasm comes into view more conspicuously than else- 
where. The granules are connected freely by intervening deli- 
cate strands, which themselves often show a row of finest 
granules. The granules, as a whole, are too crowded to permit 
decision as to whether a continuous reticulum exists. The 
chromatin granules vary in size from that of the cytoplasmic 
microsome up to much larger ones, 1 u in diameter, the size of 
the common coarse granules in the wall of vacuoles. 
Motion. — I regret not to have studied the currents of the 
body, when the animal is in those shapes in which it is only 
applied to the surface at isolated points (Figs. 3-7). At such 
times a locomotory motion, if it existed, escaped my notice. 
The animal was at rest for sufficiently long periods of time to 
permit careful study and drawing. 
When the body is linear and applied throughout its extent 
to the surface, as in Figs. 1 and 2, the motion is, in general, 
similar to that of P. vi//osa,! or of the form commonly known 
as Ameba limax. As has already been said, P. carolinensis, 
when placed on the slide, assumes the habitus of Amba 
proteus (Fig. 8). In this condition the movements are active, 
the pseudopodia being protruded in, or nearly in, a horizontal 
plane, but in any direction. The difference in appearance 
between pseudopodia into which the current is going, and those 
out of which it is flowing, is in this condition very noticeable. 
The contour of the former is smooth, the. pseudopodia having 
an appearance of plumpness and distention. In the latter case, 
on the contrary, the surface is thrown into * mulberry-like” 
folds at the ends of the pseudopods. Moreover, it can fre- 
quently be seen in such a pseudopodium that the upper surface 
is thrown into longitudinal wrinkles. These are shown in two 
of the pseudopods in Fig. 8. The appearance of these pseudo- 
podia is in perfect harmony with Bütschli's description (doc. cit., 
l Leidy. Fresh-Water Rhizopods of North America, p. 73. 
