2 Mr. H. J. Carter on the Development of Gonidia 



The internode of Nitella consists of — 1st, the cell-wall ; 2nd, the 

 green layer ; 3rd, the rnucus-larjer ; and 4th, the axial fluid, to each 

 of which parts separately let us now direct our attention. 



Cell-wall. — This, in the internode, is cylindrical, more or less 

 convex at each end, transparent, and resistent like all other cel- 

 lulose memhranes of the same kind. 



Green layer. — In contact with the inner surface of the cell- 

 wall is a layer of green bodies, which, being more or less discoidal, 

 we shall call " green disks/^ These disks, which are slightly 

 separated from each other, are arranged up and down the inter- 

 node in parallel lines, and the layer which they thus form is 

 divided into two equal parts by two transparent linear intervals, 

 which, for reasons that will appear hereafter, have been aptly 

 termed by Slack the " lines of repose." Neither these lines, nor 

 the lines of green disks wliich are parallel to them, are exactly 

 parallel with the longitudinal axis of the internode, but twisted 

 round it in a semispiral form, so that by transmitted light the 

 two white intervals, which are on opposite sides of the internode, 

 present the appearance of a cross with acute angles, which angles 

 vary in their degree with the length of the internode. 



The green disk, which is more or less ellijitical and com- 

 pressed, is composed of a vesicle of chlorophyll in which are 

 three or more granules of compressed, circular or elliptical form, 

 each of which is also, apparently, in a distinct vesicle of chloro- 

 phyll, and the whole thus grouped together form a green body 

 which is attached to, or imbedded in, the cell-wall of a third 

 vesicle. At least, this appears to be the typical form of the 

 " green disk," though its component parts arc not always di- 

 stinctly individualized ; and a vesicle with a nucleus, such as I 

 have described, may frequently be seen among the cell-contents 

 of the internode when the latter has been evacuated, whilst the 

 divisions of the green disk with a granule in each, as well as faint 

 lines between tiiem, indicative of each being surrounded by a 

 transparent vesicle, may often be seen while the disk is in situ. 

 Thus, the green layer is comj)osed of a nuird)cr of vesicles set 

 together in linear arrangement, to each of which is appended 

 the green disk mentioned. The average size of the green disk 



latter consisting of sixteen to twenty branches, alternately long and short. 

 The long branches are thrice divided, and the last division in all termi- 

 nated by a spine. The organs of fructification, which are cast together in 

 the axils of the verticil or separately in tlic centres of the umbels of the 

 branches, are, witli the terminal divisions of the latter, too small to be seen 

 distinctly by the unassisted eye. It grows here and there in the muddy 

 tanks of the island of IJondjay all the year round, and frcmi the slime and 

 foreign matter wliich collects about it, looks not unlike toad's sj)awn. Its 

 chief character, when cleansed of this, is its delicate, slender, umbelliferous 

 as])ect. 



