THE PYRENOID OF ANTHOCEROS 
F. McAllister 
University of Texas 
The single chloroplast of the cells of the gametophyte of the 
Anthocerotes, with its pyrenoid-like central region, has long been 
known. Notwithstanding this, detailed descriptions of these chloro- 
plasts and pyrenoids and comparisons with those of the algae, on the 
one hand, and with the chloroplasts of the liverworts on the other, 
seem to be lacking. 
As early as 185 1 vonMohl (14) called attention to the fact that there 
were ''wohl 50 bis 100 Amylumkorner " in the chloroplasts of Antho- 
ceros, but he did not relate them to the starch aggregations to be 
found in the green algae. 
The voluminous earlier literature on the morphology of Anthoceros, 
as far as I can determine, contains only bare mentions of the chloro- 
plasts and pyrenoids. Leitgeb (9) in fact seems to have made no 
reference whatever to these structures. 
Schimper (18) states that the pyrenoids of Anthoceros "zeigten 
nach Entfernung der Starke durch Verdunklung nur noch corrodierte, 
unregelmassig eckige Umrisse." His figures 15 and 16 are apparently 
surface views of entire, living cells and show only diffuse central 
regions which have no resemblance to the plastids as seen in stained 
material. 
Davis (5) in an account of the nuclear division and the fission of 
the chloroplasts in the spore mother cells of Anthoceros laevis makes no 
reference to a pyrenoid and nothing in his figures suggests such a 
structure. He is unable to identify plastids in the archesporial cells 
and only as these cells become spore mother cells can the single, very 
minute chloroplast be identified. This chloroplast enlarges rapidly 
and undergoes two fissions, thus forming the four chloroplasts of the 
spore tetrad. The large chloroplasts of the mature spores are filled 
with conspicuous starch grains, becoming thus "storage vesicles of 
starch." 
Campbell (3, 4) has made the most important recent contribution 
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