Archer — On Freshivater Rhizopoda. 
75 
present. But no such appearance is evident ; and I have endeavoured, 
as faithfully as I can, to repeat in Eig. 2 the appearance presented 
during the period of the extension of no less than two such temporary 
pseudopodia in the example under view. Another interpretation might 
suggest itself, which is, that the fine vertical lines seen in the rim-like 
margin presented by the edge view of the outer coat, may represent so 
many really existent minute apertures or fine canals in its substance, 
which may be of a highly elastic nature, and that when the point of 
an advancing pseudopodium pushes against one of these, the aperture 
becomes so stretched as to give passage to the comparatively thick 
conical pseudopodium ; and further, that upon its withdrawal, the elastic 
force comes again into action, and closes up the little fine passage to its 
normal dimensions. But I would myself be inclined to imagine the 
extraordinary characteristic of this outer coat, forming so remarkable a 
part of the organization or structure of the rhizopod, goes even further, 
and is even more strongly evinced. I have mentioned that from a 
definite region, from which the outer coat appears to be wanting, 
emanate the ordinary pseudopodia, and that these can be withdrawn. 
ISTow examples are however by no means rare, which, watched for a 
long time and made to roll over, show no tendency to project pseudo- 
podia nor any difference in the outer coat, which, viewed from various 
points, seems like an everywhere-present sharply-defined rim, and, as 
the case may be, more or less pilose or hairy in appearance. I am then 
half inclined to suppose that even the parts of the outer coat which 
permitted the exit of the tuft of pseudopodia, or even allowed a promi- 
nent portion of the body-mass to project, can again become closed 
up, and the creature become completely invested at all points by this 
remarkable outer coat. E'er is such a hermetically closed-in ex- 
ample torpid or encysted ;" it is perhaps quietly all the time 
assuming various contours, from a nearly globular to various bluntly 
angular forms ; and even perhaps, as I have seen more than once, such 
an example may send forth unexpectedly, mostly at one or even two 
of the corners produced, a blunt pseudopodium through the wall. On 
the other hand, that a certain amount of what may point to the reality 
of a kind of differentiation into anterior" and ''posterior" end^s, may 
be said to be evinced, not only by the frequency with which examples 
present themselves with the pseudopodia confined to one space only, but 
also by the fact, so far as it goes, that the '' nucleus" appears usually to 
occupy a position at the side remote from that of the pseudopodia! 
region, ' thus perhaps offering a certain amount of analogy to several 
other forms of Rhizopoda, where anterior and posterior extremities are 
distinctly pronounced, and in which the ''nucleus" always occurs 
behind. 
In the progress of our ideal building up of the form now under con- 
sideration, and in our gradual advance from within outwards, I pur- 
posely left in abeyance a characteristic evinced by the sarcode body- 
mass — one, however, which appertains to it in common with [a great 
many other Rhizopoda, and to that body-mass itself I must for a 
