Jan., I92i] WIGGANS — OSMOTIC CONCENTRATIONS OF GUARD CELLS 
37 
The second curve shows the results of observations made on a check 
plant. With this exception all other tests at Columbia with cyclamen were 
made on the same plant. The perfect accord between these two plants, 
however, seems sufficient proof that the first plant was a normal one. 
toAA.. g/^./v,. /Oa/vx. 2f^» ^/?>H. 
Fig. 5. Cyclamen. Observations made at Columbia. 
Iresine 
Figure 6 gives the results of observations on Iresine in a graphic manner. 
Curve (a) shows a rise in the osmotic concentration in the forenoon and a 
subsequent fall in the afternoon, with a maximum difference between the 
osmotic concentrations of the guard cells and the cells of the epidermis of 
6.78 atmospheres. Curves {h) and (<:) show a much greater rise in the 
forenoon and consequently a much greater fall in the afternoon than curve 
(a). Likewise the difference between the osmotic concentrations of guard 
cells and cells of epidermis is greater. The maximum difference amounted 
to 28 atmospheres. 
Beet 
Figure 7 shows the results of observations made on young beet plants 
at Columbia, Missouri, on January 4, when the sunshine was fairly constant 
