221 
with each other (figs. 25, 26). The motions of Protamoeba 
primitiva, the protrusion and retraction of the processes 
which vary frequently in number, form, and size, though 
always simple, take place very slowly. In this particular, 
it differs essentially from the Amoeba Umax described by 
Auerbach, 1 which is otherwise the most like it of all known 
Amoeba-forms, leaving out of view, of course, the want of a 
nucleus and of the contractile vesicle. 
The whole body of Protamoeba primitiva is absolutely 
structureless and homogeneous. There is no apparent 
difference between a more tenacious outer and a softer 
inner sarcode mass. Such a difference is perceptible in most, 
perhaps in all, true Amoebae. One can usually easily dis- 
tinguish between the firmer outer layer, which is homogeneous 
and not granular (Ectosarc), from the thinner fluid inner 
parenchyma (Endosarc), which is filled with granules. 
Sometimes these two layers pass insensibly into one another, 
in which case the Ectosarc becomes always softer and more 
fluid as it approaches the interior ; sometimes both appear 
pretty sharply defined, so that one can even designate the 
outer layer as a membrane (Auerbach). In the Protamoeba 
nothing whatever can be observed of this division of the 
Plasma into Ectosarc and Endosarc, not even on the appli- 
cation of chemical re-agents. Rather is the whole body 
formed of one and the same similar substance, which is 
tolerably tough and consistent, and displays the ordinary 
micro-chemical reactions of albumen (Plasma). 
In some Protamoebae the sarcode mass of the body is 
entirely clear and hyaline ; in others, again, it is obscured by 
a larger or smaller quantity of colourless dark oleaginously 
shining granules, insoluble in acetic acid. Most of these 
granules are very fine, but a few are larger, and of measure- 
able size. The variable number and size of the granules, 
their complete absence in some, and their abundance in other 
individuals, is probably dependent, as in the previously de- 
scribed Monera and in the Rhizopoda, on the change of sub- 
stance, on the larger or smaller quantity of nourishment 
taken, and the assimilated ingredients. 
I did not succeed in directly observing the taking of nourish- 
ment by means of the pseudopods in Protamoeba. But I could 
experimentally prove the absorption of small solid particles 
into their homogeneous sarcode body, by placing a small quan- 
tity of very finely divided indigo in the surrounding water. A 
few hours later, many Protamoebae had absorbed one or more 
1 Auerbach, “UeberdieEinzelligkeit der Amceben,” ‘Zeitschr. furWiss. 
Zool.,’ 1856, vol. vii, p. 412, Taf. xxii, figs. 11 — 16. 
