242 BOTANICAL GAZETTE [APRIL 
depositing starch in their interior, and made out that the little 
granules in the end vacuoles are rhombic plates with sharp angles, 
composed, as he discovered by tests, of gypsum. DEBary used the 
term Amylonkerne for the pyrenoids because of the many analogies 
they offer to the cell nuclei. He had discovered by means of the 
iodin reaction that the outer layer is starch, and by means of the red 
coloration with sugar and sulfuric acid that the central body is com- 
posed of protein. He described the starch which appears in the 
outer layer as either forming a homogeneous shell on the outside of 
this central body, or in the cells rich in starch as composed of grains 
that give to the pyrenoid an irregularly cracked appearance. DEBARY 
was the first to give an adequate account of the appearance and 
chemical constitution of this body in Closterium, and little of real 
importance as to its chemical nature has been added since. 
FISCHER (7) examined the crystals in the end vacuoles both as to 
their origin and composition. In his opinion they originate in the 
plasma, in which he claims there are many of them, from which they 
wander into the vacuoles. 
L&TKEMULLER (13) and a number of other observers have studied 
the structure and the beautiful and characteristic markings on the 
cell walls of the different species. 
Later authors, working on other forms, have found little to correct 
in DeBary’s account of the appearance and chemical composition of 
pyrenoids, but DEBary gave no adequate suggestion as to their 
relation to starch formation. TrmBERLAKE (22) has reviewed the 
literature fairly thoroughly, and as little has appeared since his time 
all that will be necessary is a brief account of the pone called in 
question in this paper. 
According to Scumrrz (18), who was the first to observe and 
figure the process, the pyrenoid reproduces by the simple method 
of pinching in two, the starch mass being divided between the two 
daughter pyrenoids and being replaced by growth on their sides 
where the division had occurred. ScuMrrz’s work, which was done 
on Hyalotheca, has been confirmed by CHMIELEVSKY (3) 0D Spiro- 
gyra, KLEBAHN (9) on Cosmarium, Karsten (8) on Grammato- 
phora, STRASBURGER (20) on Zygnema, and TIMBERLAKE (21) 0” 
Hydrodictyon. In addition to reproduction by division, it is fre- 
