GOG MR. S. LE M. MOOKE's STUDIES 



the same relation holds with the two succeeding layers, and with 

 the outermost layer of granular cells, but deeper down I have 

 failed to trace any dual connection. The cells of the middle zone 

 are more or less ovoid in outline, with the exception of the inner- 

 most ones, which are lengthened out more or less perpendicularly 

 to the surface, and often correspondingly narrowed. From the 

 extremity of each of these latter cells a filament of protoplasm 

 runs into one of the cells of the central zone, union occurring, in 

 all observed cases, near an end of this cell (fig. 23). The central- 

 zone cells course irregularly, but with a general up-and-down 

 direction, through the frond, accompanied by rows of smaller cells 

 with granular contents ; they are greatly elongated and somewhat 

 clavate at the ends, and united each by a slender thread of proto- 

 plasm to its supra- and subjacent fellow, but never with their cir- 

 cumjacent neighbours. Examination with high powers failed to 

 resolve the threads, nor could their division in the neighbourhood 

 of the nodule be ascertained (fig. 24) . Similar structure is pos- 

 sessed by Furcellaria, from which Polyides differs so slightly as 

 scarcely to be distinguishable, except when fruiting. 



Cebamitjm rcbrum*. — The branches of this type are com- 

 posed of an axial range of large round cells, covered over with 

 much smaller ones, and with others intermediate in size packed 

 in the intervals left between the central cells. Fig. 25 a shows 

 two of the large cells, and the way in which they run towards 

 each other by means of wide pits. The cells have, as is usual in 

 the Florideae, a dense layer of protoplasm investing the more fluid 

 contents, which are granular and contain crystalloids. The pro- 

 toplasm of the pits is either apparently homogeneous or distinctly 

 granular ; over it can usually be traced a delicate limiting layer. 

 The pits do not meet, owing to the interposition of a plate of 

 membrane riddled with fine pores, through each of which passes 

 a fine strand of protoplasm into the pit of the adjoining cell 

 (figs. 26, a & b, 25 b). The membrane is circumscribed by two 

 annular pieces of highly refractive substance, and presenting, as 

 it itself does, all the reactions of protoplasm, one belonging to 

 and surrounding the distal end of each pit, but so closely placed 

 are they as to be easily mistaken for a single piece. These pieces, 

 together with the membrane, will be spoken of as forming a 

 " ring." In longitudinal section the central cells appear as so 



* T suspect that this may be referable to some other species ; for the axial 

 cells of other specimens (typical and varietal) of C. rvbrum which I have had 

 the opportunity of examining all have much shallower pits. 



