3 06 Carter . — Studies on the Chlor op lasts of Desmids . /K 
ever, quite similar to that of the ordinary small species of Staurastrum . 
There is an axile mass of chloroplast in the centre of the cell containing 
typically one pyrenoid, and a biforked lobe running into each angle of the 
semi-cell. Each plate or lobe radiating from the central axile mass is 
shaped so as to project slightly into both the short processes of that 
particular angle . 
St . Ophiura . 
There is not much difference between the chloroplast of this species 
and that found in so many of the smaller species. In the latter, the lobes 
of the chloroplast given off from the central axile mass arise immediately 
opposite the angles of the cell into which they stretch, each one forking to 
form two plates, the two plates in any angle having been formed, therefore, 
from one single lobe (Fig. 8). In St. Ophiura , however, the lobes of the 
chloroplast do not arise opposite the arms of the cell, but between them 
(Figs. 2 6 and 27). The semi-cell is provided with a whorl of about eight 
hollow processes near its apex, and at the bases of these arms the large 
lobes of the chloroplast corresponding in number to the arms of the cell 
are drawn out at the apical region of each lateral edge to form a series of 
long attenuated projections which number twice as many as the massive 
lobes of the chloroplast given off from the central axis (Figs. 26 and 27). 
The projections enter the nearest hollow process of the cell-wall, and each 
arm, therefore, contains two projections, but these two have not been 
produced from one lobe of the chloroplast, but from two adjacent lobes 
(Fig. 27). 
The chloroplast is very regular in shape, and constant in its form, 
showing practically no variation other than the occasional occurrence of 
more than one pyrenoid in the middle of the cell. 
St. Ar disc on. 
The chloroplast in this species differs from the ordinary form in that 
only one projection is given off from the axile mass into each arm of the 
semi-cell instead of two (Fig. 29). Each half-cell is provided with fifteen 
hollow processes which are arranged in a definite way, and the form of the 
chloroplast naturally depends to some extent on this. The fifteen arms 
are arranged in two whorls, a whorl of six arms round The apex of the 
semi-cell, and a larger whorl of nine round the broadest part, lower down. 
The large central axile mass of chloroplast contains a single pyrenoid, and 
gives off a single projection to each of the arms, but the projections running 
into the two whorls seem to be related in a particular way. They broaden 
out from the arms towards the axis, and certain projections filling particular 
arms of the lower whorl seem" to be connected with corresponding projec- 
tions running into closely associated arms of the upper whorl, as if at these 
