94 
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EXPLANATION OF FIGURES IN PLATE VIII 
All figures were drawn with the aid of a camera lucida. A Zeiss 2 mm apochro- 
matic objective with an 8 compensating ocular (magnification about 1,400) was 
used for all figures except Figs. 7, 9, 20, 21, and 22 which were drawn with a 12 
ocular. 
Fig. I. A somewhat flattened chloroplast situated in a deeply lying cell of a 
mature thallus. The pyrenoid is compact and is made up of bodies which stain a 
dull red. 
Fig. 2. A large, thick chloroplast from a surface cell of a mature, active thallus. 
The pyrenoid is cut slightly tangentially so that not all of the bodies appear as discs. 
Fig. 3. A very thin chloroplast from a surface cell of a thin thallus. 
Fig. 4. A surface view of a large, active plastid. The faces of the starch 
grains show rather than the edges and the pyrenoid bodies appear less angular. 
Fig. 5. A large plastid cut slightly obliquely. 
Fig. 6. A cell from near the growing point of the thallus showing the small 
chloroplast with its pyrenoid made up of not more than 25 to 30 pyrenoid bodies. 
Fig. 7. A plastid in the vicinity of the growing point showing the pyrenoid 
bodies apparently multiplying by fission. 
Fig. 8. A plastid in which there is a gradual transition from the loose mass of 
brilliantly red-stained pyrenoid bodies into the blue stained starch grains. 
Fig. 9. Two archesporial cells just above the foot which show the single in- 
distinct plastids. 
Fig. 10. A spore mother cell the single plastid of which has many scattered 
bodies stained deeply with the violet stain. These bodies are probably very minute 
starch grains. 
