Physiology of some Zoophytes. 397 
nutrition of these bird-head processes than with their movements. 
It would be very interestmg to ascertain the functions of these 
complex appendices to the polypidom. Their movements are 
quite independent of the polypes, and continue for days after 
these are dead. The hollow processes of the polypidom, at least 
those next the outer edges, to which these bird-head processes 
are attached, sprig from the upper surface of canals which 
communicate with the interior of the spines, the ovary-capsules, 
and also by lateral apertures with the interior of the cells next 
them. Can these organs assist in circulating water along these 
canals 2% 
The body of the polype is very small when compared with 
the length of the cell, so that when it enters the cell, the gullet 
and intestine are not folded upon themselves as in Cellularia 
reptans and so many other of the ascidian polypes, but are sim- 
ply thrown into a curve. It has fifteen or sixteen ciliated tenta- 
cula considerably longer than the body: the cilia are short, thick 
and numerous. In this polype, as in the Crista chelata and 
Alcyonidium parasiticum, there is not so marked a division be- 
tween the stomach and the part which has been termed the ap- 
pendix, as in Cellularia reptans and C. seruposa. Brownish gra- 
nules and minute cells are observed on the inner surface of the 
stomach, the gullet and commencement of intestine. Ciliary move- 
ments are distinctly seen in this as m the other ascidian polypes 
examined on the inner surface of the pharynx, gullet, stomach and 
first portion of intestine. In some specimens the polypes were 
very active, darting back into their cells when disturbed, and 
immediately after agam protruding themselves. When left un- 
disturbed, they at short intervals partially withdrew into their 
cells, and immediately after again emerged and spread out their 
tentacula. The movements of the cilia attached to the tentacula 
appear to be in this, as in other ascidian polypes, under the con- 
trol of the animal. They remain quiescent when the tentacula are 
withdrawn within the cell; and even when extruded their move- 
ments are occasionally for a time suspended. There can be no 
doubt that they can act also involuntarily, for they may be seen 
in full action upon detached portions of the tentacula. Very ex- 
tensive contractile movements were very frequently observed in 
the pharynx, gullet and stomach. The arrangement of the mus- 
cles, by the action of which the polype protrudes and withdraws 
itself within the cell, appears, as far as I could trace them, similar 
to those in Cellularia reptans and scruposa. The greater number 
of specimens were provided with ovary-capsules, placed upon the 
thickened superior margin of the cells. In some specimens pro- 
* This is a mere conjecture thrown out for future investigation. 
