96 Proceedings of the Royal Irish Academy. 
larger in proportion, as this generally occupies in this form a compa- 
ratively considerable extent of the hody, and, that, therefore, so far as 
I can yet form an opinion, it should rather be regarded as equivalent 
to the body dyed red in the example in Fig. 7, that is •presumably 
homologous with the vesicula intima (' ' Einnenblase, " Haeckel). If, 
indeed, this be really so, then it may be asked : where is the structure 
siuTounding it or the central capsule itself? Perhaps, then, the answer 
to this query may be, that the latter is not yet formed, and that the 
vesicida intima is the first produced. On this point I may call to 
mind, that Haeckel himself informs us that a time exists in the young 
condition of a veritable and altogether typical marine Radiolarian, in 
which no central capsule" exists.^' 
Having thus, in the case of ^. spmifera, been able to demonstrate, at 
least in undoubted typical examples, two differentiated structures, one 
within the other, which may seemingly as yet legitimately be inter- 
preted as central capsule" and inner vesicle" Central-kapsel" 
and ''Binnenblase"), I was naturally desirous to experiment upon the 
form described by myself in my preceding Fasciculus, Acanthoeystis 
Pertycma, and, fortunately, some specimens lately turned up, though I 
regret I have been unable to prepare a figure in time for insertion in 
the present Plate. In my previous description of A. Pertyana, I stated 
that no central capsule" nor ^'nucleus" could be made out, nor 
indeed can such be perceived by mere examination of an ordinary liv- 
ing example ; it is to be regretted that I had not at command at that 
time Eeale's useful carmine fluid, for its application has disclosed at 
least an equivalent structure to that in A. spinifera. In this form, 
however, the result of the application of this re-agent was not quite 
the same as in the case of A. spinifera ; for, though a smaller round 
central body took quite as high a colour as that in that species, yet, 
unlike it, the presumable central capsule" likewise became compa- 
ratively highly coloured, but by no means so intensely as the more 
minute inner body, both one and the other becoming individually very 
clearly marked off, with a sharp outline. 
Of course the appearances presented in even both forms, resulting 
from the experiment described, might be capable of a different inter- 
pretation — that is, that these structures, in place of central capsule" 
and ''inner vesicle" may represent rather ''nucleus" and "nucleolus ;" 
but I should myself as yet be more disposed to accept the former view, 
supported as it is by the analogy of the structure of the marine forms 
— a view in which I imagine most other observers will rather be in- 
clined to acquiesce. Bearing on this point, I may perhaps have an 
opportunity to offer some notes on a future occasion relating to certain 
other rhizopods. 
Eegarded, however, in either light, the presence of these central 
structures in each of the conjoined examples in Fig. 7, would seem to 
go to indicate that they are really two distinct individuals mutually 
^ Loc. cit., p. 530. 
