VOLUME XLI1X NUMBER 4 
BOTANICAL GAZerIe 
APRIL srg1I0 
THE CELL STRUCTURE OF CLOSTERIUM EHREN- 
BERGII AND CLOSTERIUM MONILIFERUM 
B. F. LUTMAN 
(WITH PLATES XVII AND XVIII) 
Little has been contributed to our knowledge of the chromato- 
phore and pyrenoids of Closterium since the time of NAGELI and 
DrEBary, though several investigators have worked on the cell division, 
conjugation, and peculiar mode of locomotion of these plants. 
NAGELI (5) described the chromatophore, nucleus, end vacuoles, 
pyrenoids, and cell wall of the genus. He figures only C. moniliferum 
and C. parvulum, but mentions eleven other species as belonging 
to the genus, not including, however, C. Ehrenbergit among them. 
The chromatophore as described by him consists of three or more 
chlorophyll plates whose inner edges rest in the axis of the cell and 
whose outer edges extend to the cell wall. In optical cross section, 
obtained by examining the plant when it was standing on end, the 
chromatophore appeared to be made up of 3 to 15 plates extending 
radially from center to periphery. The nucleus he describes as a 
clear sac containing a denser body. In the colorless ends of the plant 
body are the clear vacuoles containing little black granules showing 
a motion which he calls molecular; these vacuoles are usually spher- 
ical, although at times irregular in shape. The pyrenoids, “little 
chlorophyll sacs,” are arranged in C. moniliferum and C. parvulum 
in a single row of 2 to 20. The cell wall is striate. NAGELI’s 
figures show, besides the external views, optical cross sections of 
C. moniliferum and C. parvulum. ‘These are the only figures extant 
~ and they have been copied by OLTMANNs (17) and Lortsy (12). 
DeBary (5) also described Closterium, but adds little to NAGELI’s 
account except that he recognizes the pyrenoids (Amylonkerne) as 
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