THE AMOEBA. 189 
other, and more obscure ones, which possess the highest 
physiological interest. 
The animal substance forming the body of the Amoeba is 
sarcode , similar, in many respects, to that investing the living 
Sponges, and producing the calcareous shells of the Forami- 
nifera. In the Amoeba this sarcode is separable into two parts, 
an outer and an inner one. To the first the convenient name 
of ectosarc (fig. 1, ec) has been given; whilst that of endosarc 
(fig. 1, en) has been applied to the second, or inner substance ; 
and as these appear to be the best names hitherto suggested, 
I shall employ them in the following remarks. The ectosarc 
is clear, transparent, and colourless, containing permanently 
few or no granules, or foreign bodies of any kind. This trans- 
parent aspect has led Mr. Carter to apply to it the name of 
diaphane. The tissue is capable of extension and contraction, 
being sometimes prolonged into radiating pseudopodia, which 
at others are drawn back into the central mass of the creature. 
But here we at once enter upon debateable ground. Mr. 
Carter affirms that this ectosarc is invested, in some instances, 
by a very thin transparent pellicle, which is elastic and tena- 
cious, admitting of rupture and readily healing again, whilst 
from iodine communicating a violet tinge to it, he assumes 
that in its chemical composition it is related to starch. On the 
first of these points, viz., the existence of a pellicle, Auerbach 
entertains a similar view. On the other hand, Dr. Wallich has 
never been able to discover any true pellicle, and he describes 
some experiments which indicate that, in this instance, the 
iodine proof is fallacious. I have never detected any pellicle, 
and am disposed to doubt its existence. The nature and origin 
of the ectosarc are also debated questions ; but before 
noticing the points in dispute, we may glance at the endosarc. 
This is a modification of sarcode, which is darker than the 
ectosarc, apparently from its being crowded with minute 
molecules, as well as with various organs belonging to the 
animal, and with foreign particles which have been incepted 
or introduced into its interior as food. In the midst of these 
are often found some angular crystalloid bodies (figs. 11, 12, and 
13) of doubtful origin, which Mr. Carter thinks may be 
oxalate of lime, and analagous to the raphides of plants; as 
well as some refractive oily-looking atoms, which he regards 
as fat globules ; whilst in one case Auerbach is said to have- 
found starch. But, besides the above elements, we have some- 
more peculiar objects usually present in the endosarc, 
especially nuclei, contractile vesicles, and food vacuoles. 
One, or occasionally more nuclei are usually present in each 
Amoeba (fig. 1, n). The nucleus is a small granular body, 
believed by Dr. Wallich to be inclosed within a true capsule 
