Physiology of some Zoophytes^ 397 



nutrition of these bird-head processes than with their movements. 

 It would be very interesting 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, spring 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?* 



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 Crisia 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 Cellulayna reptans and C. scruposa. 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 in 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 again 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 withdrawn within the cell ; and even when extruded their move- 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 speicimens 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. 



