474 THE MICROSCOPE. 



laria indivisa, -when magnified one hundred times, a 

 current of particles was seen within the tubular stem of 

 the polype, strikingly resembling, in steadiness and 

 continuity of its stream, the vegetable circulation in 

 the chara. Its general course was parallel to the slightly 

 spiral lines of irregular spots on the surface of the tube, 

 ascending on the one side, and descending on the other ; 

 each of the opposite currents occupying one-half of the 

 circumference of the cylindric cavity. At the knots, or 

 contracted parts of the tube, slight eddies were noticed 

 in the currents ; and at each end of the tube the par- 

 ticles were seen to turn round, and pass over to the other 

 side. 



" The particles carried by it present an analogy to those 

 of the blood in the higher animals of one side, and of the 

 sap of vegetables on the other. Some of them appear to be 

 derived from the digested food, and others from the 

 melting down of parts absorbed ; but it would be highly 

 interesting to ascertain distinctly how they are produced, 

 and what is the office they perform, as well as the true 

 character of their remarkable activity and seemingly 

 spontaneous motions ; for the hypothesis of their indi- 

 vidual vitality is too startling to be adopted without good 

 evidence." 



Respecting the singular property of the head dropping 

 off, Tubularia indivisa, Sir J. G. Dalyell observes, " The 

 head is deciduous, falling in general soon after recovery 

 from the sea. It is regenerated at intervals of from ten 

 days to several weeks, but with the number of external 

 organs successively diminishing, though the stem is always 

 elongated. It seems to rise within this tubular stem front 

 below, and to be dependent on the presence of the internal 

 tenacious matter with which the tube is occupied. A head 

 springs from the remaining stem, cut off very near the 

 root ; and a redundance of heads may be obtained from 

 artificial sections. Thus, twenty-two heads were produced 

 through the course of 150 days from three sections of a 

 single stem." 



Included in this family are the T. ramous, T. ramea, the 

 "branched pipe-coralline, with its dark brown stem termi- 

 nating in clusters of red and yellow polyps ; and the 



