Archer — On Freshwater Rhizopoda. 95 
vents the intrusion of any of the granular contents of the extra-cap- 
sular" region of the inner sarcode body. "We have then, in the con- 
joined specimen, shown by my Fig. 7, the outline of this ''central 
capsule" still faintly indicated, but which has not acquired any higher 
colour from the carmine solution than that of the extra-capsular re- 
gion ; but the minute round body in the centre of each, as before alluded 
to, has imbibed the colour very strongly. JSTow the question at once 
presents itself, what does this little rounded central (here highly dyed) 
body represent ? If, indeed, observers will go so far as to conceive 
that the structure first described by Greeff in this form be truly homo- 
logous with the central capsule of the marine Eadiolaria, then I would 
venture to suggest that the more minute (highly dyed) body occupying 
the centre of each of the conj ugated individuals in the figure, may re- 
present the vesicula inti^na, or inner vesicle ('' Binnenblase, " Haeckel). 
If, indeed, I may be correct in that assumption, then this will be the 
first instance (so far as I am aware) in which that element of the organi- 
zation of atypical '' Eadiolarian" has been perceived in any fresh-water 
representative. Still it is a portion of the structure that I believe 
would be quite impossible to detect or see in this form in the ordinary 
condition of the fully-grown rhizopod, owing, I may presume, to the 
solid or opaque appearance of the '' central capsule" above alluded to. 
At least, I fear, I should never myself have suspected the existence or 
have seen it in such examples without the application of the re-agent. 
But the experiment illustrated by the figure having shown the 
actual existence of such an inner body, leaving its precise homology 
in abeyance, I naturally was anxious to refind some of the more 
minute, and, therefore, less opaque and less granular forms, which, as I 
have said, I would be much inclined to regard as younger examples of 
A. spinifera, in order to submit such to a more critical examination. 
Eortunately a gathering, just made in County Tipperary, revealed a few 
such, and of one of these I endeavour to give a portrait in Fig. 8, 
which indeed though so minute, seems to give a certain indication of the 
yellow globules, though faint in colour. I had now, however, no clifS.- 
culty in perceiving in the centre of such a minute example a delicate 
pale and colourless globular little body, whose nature can admit of but 
two interpretations, one only of which, of course, can be the true one. 
It is either a structu.re quite homologous with that represented in 
Greeff' s figure, and indicated also in mine (Fig. 7), in fact, the presumable 
'' central capsule," or else it represents the inner minute body, so 
deeply dyed in the example figured. Probably, had the very small 
specimens in this particular gathering been sufiiciently numerous, the 
experiment of the application of the carmine solution would have 
assisted to decide the point ; I could not succeed, however, as yet in 
bringing it to bear on any of those minute specimens. But, although I 
must leave the question an open one as yet, I may draw attention to 
the consideration, that, if the little central body in Fig. 8 really repre- 
sents the same body as figured by Greeff, and readily seen in examples 
taken by myself — the presumed ''central capsule" — it ought to be 
