2 7° Carter . — Studies on the Chloroplasts of Desmids. III. 
actually be crowded together, they are nearly always confined to the limits 
of the axis itself. The axis of the chloroplast gives off four massive lobes 
which sometimes fork towards the periphery, ending with toothed or smooth 
edges near the cell-wall (Figs, 9, 20, and 32). In other cases the plates are 
bent so as to embrace a considerable part of the cell-wall in a parietal 
manner (Figs. 18 and 20). Very often more than four plates are to be seen, 
the extra ones being smaller and inserted between the main lobes, stretching 
towards the front faces of the cell (Figs. 3, 4, 7, 3 8 , and 19). The thickness 
of the plates varies considerably ; in some individuals only sharply defined 
fringed edges lie against the cell-wall (Figs. 1, 2, 6, 16, and 17), whilst in 
others the whole chloroplast may be much more massive, and the cell-wall 
may be almost entirely covered by the broad edges of the ridges (Figs. 8 
and 31). Such differences in the character of the chloroplasts are doubtless 
to be correlated with the amount of stroma starch contained in them. 
C. caelatum and C. speciosum. 
In these two species the chloroplasts only differ from those of the above 
five species in the rather larger number and more simple form of the plates 
radiating from the axis. The first-mentioned species has about eight such 
plates (Fig. 11), whilst in C. speciosum there are about ten (Fig. 30). In 
both cases all the ridges are quite similar to each other, except that those 
running towards the lateral edges of the semi-cell are naturally larger than 
those which go towards the front faces. The plates or ridges rarely branch, 
and end simply on reaching the cell-wall, no attempt at the formation of 
parietal films of chloroplast being observed (Figs. 10, 28, and 29). 
C. cucurbita and C. curtum. 
In those species examined having cylindrical cells the chloroplasts are 
not very different from those already described. C. cucurbita has in each 
semi-cell a central axis containing usually one pyrenoid, and from this 
radiate about eight very distinct thin plates, which end near the cell-wall 
with lobed or fringed edges (Figs. 14 and 15). C. curium has a chloroplast 
which is quite similar to that of C. cucurbita. Its simple axis is usually 
provided with a single pyrenoid, and there are about eleven plates radiating 
towards the periphery, ending with sharp edges against the interior of the 
wall (Text-fig. 1, A and B). Occasionally the ridges were observed to be 
twisted slightly in a spiral. In these two species, as in all the others dealt 
with so far, the axis does not always extend right to the apex of the semi- 
cell, and where this is the case the radiating plates extend beyond it until 
they reach the extremity of the cell, enclosing a chlorophyll-free space 
between them ; cf. Figs. 1, 14, 16, 17, 28, and 29. This is very pronounced 
in young semi-cells. 
