174 SOME OBSERVATIONS ON THE 



particles were various in size ; some very small, others appa- 

 rently aggregations of smaller ones ; some were globular, but 

 most were without a regular form of any kind ; they flowed at 

 a uniform rate, in distinct currents, upwards and downwards, 

 each current occupying half of the circumference. There were 

 slight vortices in the current at certain nodous portions of the 

 tube : no passage of particles was observed between the tube 

 and the stomach. The action between the stomach and 

 mouth was different from that in the tube. The mouth 

 became swollen by a flow from the stomach, which continued 

 about a minute ; the contents of the mouth then returned to 

 the stomach, which expanded, — the mouth at the same time 

 contracting, — during which operation the connecting orifice 

 was seen distinctly to open, and it continued so on the return 

 of the flow to the mouth, till the stomach became nearly 

 emptied; the orifice then gradually closed ; and again re-open- 

 ing, allowed the fluid to repass into the stomach : the intervals 

 between each contraction of the orifice were very nearly eighty 

 seconds. 



The second observation is on Sertularia pluma ; the spe- 

 cimen examined contained 400 to 500 polypi. " All the 

 polypi were connected together by a soft granulated matter, 

 which extended throughout the interior of the branches, stem, 

 and root. With a power of 300,*^ a current of particles, 

 varying in size and form, was observed running along the 

 axis of this soft matter. It flowed in one channel, alternately 

 backwards and forwards, through the main stem and lateral 

 branches of a plume, and through the root, as far as the opacity 

 permitted its being traced : sometimes it was seen to continue 

 into the cells. The stream was, throughout, in one direction 

 at one time ; it might be compared to the running of sand in 

 an hour-glass, and was sometimes so rapid in mid-tide, that 

 the particles were hardly distinguishable ; but it became much 

 slower when near the change. Sometimes it returned almost 

 without a pause ; but at other times it was quiet for awhile, as 

 the particles took a confused whirling motion for a few seconds, 

 the current afterwards appearing to set the stronger for this 

 suspension. The whirling, or starting motion, took place 

 sometimes at one, sometimes at another part of the stem and 

 branches during the intervals of the currents. Five ebbs and 



*^ Oliservcil also witli a invvir oi ICO. 



