10 GEORGE BUSK. 
firmly attached. In many instances the filament may be 
seen entering the cavity of the empty shell and coiling 
about within it.! 
It is difficult to imagine how this subdivision of the 
distal end of the tube or stem can take place, unless at 
that part there is active power of growth, as at the ex- 
tremities of the root fibres in plants, though in a different 
and at present unknown way. Anda still more remarkable 
fact is the power of adaptation to the environment 
that is possessed by these delicate filaments, which might 
almost lead to the conclusion that an active living power 
resides in even the ultimate fibrille. 
In Kinetoskias the peduncle, as I have observed, repre- 
sents a radical tube, or rather, it may be said, a coalesced 
bundle of tubes. 
The wall of the peduncle, in the living or fresh condition, 
is described by Sir C, W. Thomson as being as clear as 
glass, and it retains this transparency scarcely impaired 
even after long immersion in alcohol. Unlike the radical 
tubes in all other Polyzoa that I have examined, the 
corresponding structures in Anetoskias have no action on 
polarised light.” Though very thin the wall is extremely 
tough, and beyond an obscure appearance, in the contracted 
state, of a very delicate, longitudinal, irregular striation, no 
trace of structure can be observed in it. 
Within, as I have stated, the remains of a very delicate 
endosare or cyst may be observed, as represented by a few 
scattered, minute nuclear bodies, and irregular branching 
filamentous strings. ; 
I have already cited Professor Smitt’s account of the mode 
of formation of the radical tube or stem and sheathing mem- 
brane in J. arborescens, and this, in the main, is equally 
applicable to A. cyathus and A. poctllum. 
In fig. 5 is represented the bifurcation of one of the 
branches in the latter species, just above the point at which 
the branches are connected by the sheathing, umbrella-like 
“ale 
n this figure are shown delicate, dilated, radical tubes, 
passing across from one branch to the other. These ttibes 
arise from the constricted part of the 2owcium behind and 
immediately above its point of origin from the subjacent 
one. And they are apparently inserted into the correspond- 
ing point of the zoccia in the opposite bratich. The ttibes 
1 This arrangement, however, is equally well shown in many other of the 
abyssal forms of Bugula, Bicellaria, and other genera. 
2 Which would probably indicate the absence of any calcareous element, 
