147 
drica (a form I have never encountered) a skin (*‘ peau’’), 
whilst in respect to P. spherica they are silent in this regard ; 
but it is, I imagine, exceedingly probable that, so far as con- 
cerns this, the account given of each should coincide, and 
were most probably meant by the authors to be so under- 
stood. But beyond the fact that the figures represent the 
forms as possessing a quite smooth surface and sharp outline, 
there is no evidence afforded of the so-called “skin.” The 
question, then, becomes what they meant exactly to convey 
by that term; but presumably it must have been not a sepa- 
rable integument enclosing the sarcode-body (certainly not a 
test or “ coque’’), but only a more dense and hardened, or 
rather toughened, exterior to the body, forming therewith a 
single inseparable whole, both being in complete organic 
union, and thus, only that it is less yielding, hardly, if at all, 
more than what has been attributed even.to Amceba itself by 
some observers, as Auerbach and others. And, in fact, [had 
myself several times met with the rhizopod I am still disposed 
provisionally to regard as Claparéde and Lachmann’s form 
alluded to, and that without perceiving any further differen- 
tiation into body and integument than that I should suppose 
those authors were inclined to attribute to it. 
Hence the experience, presently to be adverted to, gained 
from the preparations of both my forms under Beale’s carmine 
fluid (fig. 16), and under acetic acid (fig. 12), does not appear 
to militate against the correctness of the identification of the 
first form here figured with Play. spherica, for in the living 
example this outer case, or covering, is always so closely 
applied to the body as to appear, indeed, no more than a 
smoothly bounded exterior, which might seem possibly, to a 
certain extent, to be comparable to a “ skin.” 
But although I cannot but suppose the identity of the form 
I sketch in fig. 11 to be probable, as I have mentioned, I 
regard this determination as yet as but provisional for certain 
other reasons. 
The first is that my form shows a distinct “ nucleus,” or 
body so called. Now, in this regard Claparéde and Lach- 
mann are silent concerning their Plag. spherica, but they 
distinctly state they were unable to detect this in their Plag. 
cylindrica. Still, as this is only evidence of a negative cha- 
racter, it does not disprove the identity, for, owing to the 
density of the contents, the nucleus may have been present 
in both their species, but have been overlooked by them. 
When our form (fig. 11), alluded to, is treated with the car- 
mine fluid the nucleus takes a deep dye (fig. 13), and when 
treated with acetic acid (fig. 12) it is mostly ejected, and can 
