THE PYRENOID OF ANTHOCEROS 
87 
plastids in the archesporial cells they were too minute to be distin- 
guished with the highest magnifications. So far as it is possible to 
determine, they have arisen de novo. They take the blue stain and are 
probably starch masses. Their shape and size is essentially the same 
as that of the pyrenoid bodies seen in assimilative cells. Whether they 
ever at any earlier period stain red as do the pyrenoid bodies I have 
been unable to determine. That they develop directly into the large 
starch grains to be seen in the spores is easily proven. Figure 1 1 
shows a chloroplast at a somewhat later period in which these bodies 
have enlarged greatly and are now without question starch grains. 
There seems thus to be no doubt that two different modes of starch 
formation exist in Anthoceros, the one occurring in connection with the 
pyrenoid, in cells active photosynthetically, and the other occurring 
in cells lacking pyrenoids, in which the carbohydrate is being deposited 
only. I have unfortunately up to the present been unable to get 
satisfactory material to test this experimentally. 
The chloroplasts of the cells of the assimilative tissue surrounding 
the sporogenous layer immediately above the foot contain numerous 
scattered starch grains but no traces of a central aggregation of smaller 
bodies (figure 12). If the bodies which later aggregate to form the 
pyrenoid are present in these cells though scattered, they are either 
unrecognizable among the starch grains or they are too minute to be 
detected. In some of the slightly older cells of this same layer, minute 
bodies, which may be rudimentary pyrenoid bodies (figure 13), are 
to be seen scattered through the plastid. In the central region of 
other chloroplasts are loose aggregates of similar bodies which suggest 
the pyrenoid (figure 14). Along with these bodies — usually nearer 
the periphery of the plastid — are to be seen scattered starch grains 
which seem to be the same in form and structure as those seen in 
tissues of the sporophyte and gametophyte which are exposed to 
abundant light. As will be seen from figure 15 these starch grains 
are much larger and are easily distinguishable from the minute cen- 
trally located pyrenoid bodies. Still higher up in the region of inter- 
calary growth the plastids show definite central aggregations of reddish 
stained bodies with but few or no starch grains in the peripheral 
region (figure 16). Higher up the form of the chloroplasts and 
pyrenoids becomes the same as that of those already described for the 
gametophyte (figure 17). Those plastids in the regions of the sporo- 
phyte receiving full exposure to the light seem to be identical with 
