368 MR. LISTER ON THE STRUCTURE AND FUNCTIONS 



Later in the day the imperfect new piece of shell was folded in, the stomach h 

 had disappeared and the end of the soft part within the tube was shrunk to a conical 

 form, all dilatation and contraction (of which there were some remains in the morn- 

 ing) having ceased ; another discharge had taken place from the mouth, and a consi- 

 derable one from the neck, when the tube acquired a defined end {a 5) ; and between 

 the shell and the conical soft part a vacant space had been gradually left. Into this 

 was now admitted from the neck some granulated fluid matter, which flowed over 

 the conical surface, and after some agitation of the particles, formed a rounded co- 

 vering to it ; semitransparent at first, but soon becoming more opake, so as not to 

 be distinguished from what it covered {a 6). The circulating particles of the tube 

 now flowed into the end and returned from it, as at a septum of Chara. 



Afterwards rapid action of large granulations and stillness alternating took place 

 within the neck ; and in the evening the polypus was completely separated from the 

 soft matter of the tube, and dead ; its substance breaking away in a stream of dis- 

 engaged particles. The following morning some slimy matter about the end of the 

 tube was all that remained of it ; but the circulation within the tube continued as 

 before. 



The specimen was now immersed in spring water. The first eff*ect was, instead of 

 the two currents, one flow, towards the end of the tube, of roundish particles, some 

 of which escaped into the water : after this had continued a short time, the whole in- 

 ternal contents of the tube began to move forwards together, and became protruded 

 at the end like thin paste ; then for a while a clear current with few particles in it 

 flowed back between the shell and the moving mass, and showed the shell to be 

 transparent, and that the mottledness and granulations, as well as the irregular 

 lines of spots which were before seen in it, were wholly belonging to the soft matter ; 

 another circumstance analogous to what is met with in Chara. 



This single observation on Tuhularia was prolonged in the hope that the destruction 

 of the hinder arms might have proved to be part of a process of lengthening the tube. 

 Some of the later appearances were evidently the effect of disease, and the action be- 

 tween the mouth and stomach during the first day seemed unnaturally violent ; 

 yet the currents there will be seen to bear a resemblance to those which accom- 

 panied vigorous growth in Sertularia. The instance of deposition recorded stands 

 at present by itself; that of absorption will be fully corroborated. The circulation 

 in the tube exhibits a character hitherto, I believe, only observed in the vegetable 

 kingdom. 



SERTULARIiE. 



Each of the divisions Tubularice smd Sertularice,as adopted by Cuvier, includes 

 widely diff'ering genera, while they separate others that are closely allied. Some 

 which I think should be placed among cellular polypi, will be noticed hereafter ; 



