614 MR. S. LE M. MOORE'S STUDIES 



the centre of the upper cell's floor, as also of its underlying 

 neighbour's roof, is a highly refractive knob-like structure fixed 

 to the wall of partition. These knobs are what Archer calls the 

 "stoppers." The curious articulation gives origin to what he 

 terms " bottles." An idea of the method of continuity in this 

 type will be gained from inspection of figs. 55 and 56. Each 

 stopper rests upon a thin bed of membrane similar to the mem- 

 brane closing the rings of other FlorideaB ; and the wide inter- 

 cellular pit is apparently filled with the same substance. The 

 circumference of the stopper's base is continuous with the thin 

 parietaljlayer of cell-protoplasm, and can frequently be easily di- 

 stinguished as a dark line from the brighter mass of the stopper : 

 the base itself is filled up with membrane upon which the mark 

 of the pit is very clear (fig. 55). From the circumference of the 

 base of a stopper fine threads run up the pit to be similarly 

 inserted on the contiguous stopper. It will thus be seen that 

 Ballia resembles other Floridese in the method of continuity, 

 its chief points of difference being the extent to which the mem- 

 brane is developed, and the remarkable form assumed by the 

 highly refractive portions of the ring. 



The stoppers are endowed with an extraordinary power of 

 growth. Originally making their appearance, like the halves of 

 an ordinary ring, as two gleaming pieces of protoplasm upon the 

 contiguous faces of just-formed cells, between which a narrow 

 channel of protoplasm extends (fig. 58), they rapidly enlarge and 

 continue to do so, it would seem, almost without limit (fig. 57)*. 



The view here adopted is that continuity is always direct in the 

 early history of the cells, and in some cases (Chondrus, Polyides, 

 Furcellaria) persistently so ; while in others direct continuity 

 may persist in one part of the thallus, and be supplanted by the 

 indirect form in another (Ceramium rubrum, &c). The young 

 cells are placed in communication by means of a fine filament upon 

 ■which is in most cases placed a small nodule, just as a bead is 

 strung upon a thread. The ground for this statement is that in 

 surface views of the nodule only a single small central pore can 

 be seen, and that the thread itself, as slender as the single threads 

 piercing the membrane of rings, cannot be seen to undergo divi- 

 sion in passing the nodule. 



The next fact to notice is the rapid growth of the thread aceom- 

 * Several enlarged stoppers are figured by Archer (I. c. pi. xxviii.). 



