ARCHER—ON RHIZOPODA. PAF | 
or less readiness gives way to forces sometimes from within, and most 
likely sometimes from without, and in the living animal recovering po- 
sition and coherence, as, for instance, pressing on the covering glass, or 
the action of the little parasitic rotatorian previously described by me. 
In addition to the fact of finger-like protrusions of colourless sarcode 
being projected and withdrawn, one sometimes sees likewise two indi- 
viduals of A. ¢turfacea united by an isthmus (‘‘ conjugated” ?) (showing 
that the spines can recede from one another, and come back to position), 
the isthmus gradually stretched, till 1t becomes a mere connecting thread 
of sarcode, which eventually snaps, and the two examples pass away 
from one another, no trace of the place from which the mutual band 
of sarcode emanated being left. Can such examples represent the state 
of <‘ fission” (Zweitheilung), adverted to by Greef, as one of the repro- 
ductive conditions of A. turfacea ? Under ordinary circumstances, the 
circular discoid bases of the spines must leave triangular spaces between, 
quite large enough to allow of the passage forth of the ordinary pseu- 
dopodia through the medium which we must assume causes the mutual 
coherence of the spines, and this without any displacement of the 
latter. 
In this genus Acanthocystis Greef brings to notice three other 
forms; two he names as new, and the other he leaves in abeyance. One, 
which he calls Acanthocystis pallida, seems to me to differ in no respect 
from A. turfacea further than in the absence of the green colouring gra- 
nules, except that he attributes to it the existence of the bacillar or 
linear spicula said to occur along with the radial spines, and as to which, 
indeed, he is silent as regards Carter’s form. But, as I have mentioned, 
I now am quite disposed to hold these as very problematical. There 
remain only then the colourless granules to distinguish this form from 
A. turfacea. Now, quite colourless examples of what I have always 
thought could be none else than 4. turfacea often occur here ; nay, ex- 
amples present themselves with a great proportion of the body-mass 
bearing the green (chlorophyll) granules, and the remainder colourless, 
and these regions marked by a sudden transition. I think the same 
- green granules sometimes become colourless. We see sometimes Dif- 
flugiz loaded with chlorophyll granules. Raphidiophrys viridis some- 
times, but it is rarely, shows some colourless granules. I cannot 
but think, therefore, that 4. pallida is only a colourless, not at all 
uncommon, state of A. turfacea. 
But as regards another form (not named) referred to by Greef I 
would, indeed, very deferentially think he had far better ground 
to establish it as a distinct species. I mean the form he gives in his 
Pl. XXVII., fig. 18. This form seems to be distinguished from A. tur- 
facea by the want of the shorter series of radial spines—by the longer 
series, less copiously present, being, according to Greef’s account, im- 
mersed to a certain extent within the periphery of the inner body— 
and, further, by the outer sarcode region, here strongly pronounced, 
being subdivided at the outer margin into a great number of exceed- 
ingly delicate, linear, acute processes, the pseudopodia passing, just as 
