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nor contractile vesicle, and which consist throughout their 
whole bodies of a perfectly homogeneous and structureless 
mass, are well to be distinguished from the true Amoebae (Aut- 
amcebae), which alw r ays possess a nucleus, and generally also 
a vacuole, or even a constant contractile vesicle. Such abso- 
lutely simple Amoebae, the simplest which can easily be con- 
ceived, occur, for example, as transitional young stages in 
the development of the Gregarinae, from whose Navicula-like 
granular germs they, the so-called pseudo-Navicellae, are deve- 
loped. But such entirely simple Amoebae also occur as inde- 
pendent organisms, persistent in this very simple form, and 
reproducing themselves — if you please, as “ good species,” — 
and I have proposed in my ‘ General Morphology’ to separate 
them as “ Protamoeba,” entirely from the true and manifestly 
much higher organized Amoebae (Vol. I, p. 183). As I have 
only casually mentioned the Protamoeba in the passage re- 
ferred to, and besides have published nothing about it, I 
shall give a short description of this group here, in addition 
to the Monera which I have just described. 
Protamoeba primitiva, represented at figs. 25 — 30, I ob- 
served for the first time at Jena, in the summer of 1863, in 
water which I had brought from a small pond in the Tauten- 
burg forest (opposite Dornburg, on the right bank of the 
Saal). The bottom of this shallow little pond is thickly 
covered with fallen decayed beech-leaves, and in the fine 
brown mud, among the decayed leaves, I found the little 
Protamoeba, the first Moner which I had happened to meet 
with. 
If the Protamoeba primitiva is immediately transferred to 
the microscope from the fine mud in Avhich it creeps, and a 
strong light is brought to bear upon it, it commonly appears 
as a homogeneous Plasma-ball of 0 - 03 — 004 mm. diameter. 
After some time this ball begins slowdy to flatten ; its 
diameter increases to 0‘06 mm., and, at the same time, its 
circular outline becomes irregular. Then a blunt cone- 
shaped or wart-shaped projection soon begins to appear, first 
at one point, and then simultaneously at several. While this 
lengthens, stretches, and draws a portion of the remaining 
mass of the body after it, the irregular roundish outline 
becomes pear-shaped, or if several pseudopods appear to- 
gether, star-shaped. There Avere seldom more than five or 
six wart-shaped projections visible on the circumference of 
the disc-shaped flattened body. The projections or pseudo- 
pods always remain short and simple. At most their length 
about equals the diameter of the rest of the body. They 
never ramify, and tw r o adjacent pseudopods never coalesce 
