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



chamber, but by its expansion during growth gaps occur between 

 them. Fig. 28 shows the method of connection between the short 

 and long cells, and between those of either kind and their fellows. 

 The long cells are frequently clavate, and the ends are joined to 

 their supra- and subjacent fellows by saddle-shaped surfaces. 

 Their protoplasm is continuous through circumferential or scat- 

 tered pores in the closing membrane of often broadly contoured 

 rings (fig. 29 a, h, c). Similar rings serve as media of communi- 

 cation between the sides of contiguous long cells. The walls of 

 the chambers are built up of small cells, externally underlain by 

 several layers of larger ones resembling those of their roof and 

 floor. These latter cells communicate by means of rings, through 

 whose membrane a single or several strands may pass (fig. 30 a, b). 

 The connection between the external cells is by means of fine 

 nodule-bearing filaments, of whose division in passing the nodule 

 proof was not obtained. 



Of the genus Callithamnjost, a small fragment only, belong- 

 ing to an undetermined species, has come under observation. In 

 one case the achromatin fibres and commencing formation of a 

 cell-plate were well seen (fig. 31 a) . At the next stage examined 

 (fig. 31 b) the cell-wall has closed up except where it yields 

 passage to a fine thread, at either end of which is a gleaming 

 particle recognizable from the ordinary protoplasm with which 

 the young cells are gorged. Fig. 32 a shows the ring defi- 

 nitely formed ; and 32 b division of its intercellular protoplasm 

 in passing through the membrane : in this case the ring has 

 been ruptured ; otherwise demonstration of division at this stage 

 is very unsatisfactory. 



Griffithsia setacea. — The branches are composed of a 

 single range of cells with broad ends, between which, at the blind 

 end of somewhat wide pits often filled with granular protoplasm, 

 is a small thin ring provided with a membrane pierced with holes 

 over all its surface. 



Ptilota sericea. — A figure showing continuity at and near 

 the growing-points is given by Hick*. The frond consists of an 

 indefinite main axis bearing a number of opposite secondary axes, 

 themselves bearing axes of the third degree, and so on. The axis 

 of a branch is formed of scutcheon-shaped cells, each of which 

 gives origin on each side to a cell which is the basal cell of a 

 branchlet, and with which, as with its preceding and succeed- 

 * L. c. tab. 244, fig. 9. 



