ON THE ECONOMY OF CLOSTERIUM LUNULA. 57 



driven, for the most })art, back again on the precise course 

 by which they had arrived ; some, however, do enter the 

 chamber : occasionally, but very rarely, I have seen one of the 

 loose bodies escape from within, and get into this outer 

 current, in which it is carried about, until it becomes adherent 

 to the side of the frond. I am now cpiite satisfied that in the 

 case of the specimen dia'j;ram C (p. 235, Vol. II.), to which I 

 referred in your la.st number, the pressure of the glass in which 

 the specimen was enclosed had forced the endochrome so far 

 up into the chamber, that the jetting action of the fluid, nomi- 

 nally acting within the fi'ond, Avas thus made to play exterior 

 to it. 



With regard to the propagation of tlie C. Lunula, I have 

 never seen anything like conjugation, but I have repeatedly 

 seen what I shall now describe — increase by self-division. 



Let me request your readers to observe the diagram D, 

 but for the moment to suppose the two halves of the frond, 

 represented as separate, to just overlap each other ; I have 

 watched for hours the process of complete division ; one-half 

 has remained passive, the other has had a motion from side 

 to side, as if moving on an axis at the point of juncture ; the 

 separation has become more and more ardent, the motion 

 more active, until at last with a jerk one segment leaves the 

 other, and they are then under view as I have drawn them. 

 It will be seen, that in eacli segment the endochrome has 

 already a waist ; but there is only one chamber, which is the 

 one belonging to one of the extremities of the original entire 

 frond. The globular circulation for some hours previous to 

 subdivision, and for some few hours afterwards, runs quite 

 round the obtuse end of the endochrome — a, by almost 

 imperceptible degrees ; from the end of the endochrome, 

 symptoms of an elongation of the membranous sac appear, 

 giving a semilunar sort of chamber; this, as the endochrome 

 elongates, becomes more defined, till it has the form and 

 defined outline of the chamber at the perfect extremity. 

 The obtuse end — Z» of the frond is at the same time elon- 

 gating and contracting ; these processes go on ; in about five 

 hours from the division of the one segment from the other, 

 the appearance of each half is that of a nearly perfect specimen, 

 the chamber at the new end is complete, the globular circula- 

 tion exterior to it becomes affected by the circulation frovi within 

 the said chamber ; and, in a few hours more, some of the free 

 bodies descend, become exposed to, and tossed about in the 

 eddies of the chamber, and the frond, under a l-6th power, 

 shows itself in all its full beautiful construction. £ is a 



