40 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
The conclusions to be drawn from these experiments are : 
(1) That there is a difference between the osmotic concentration of 
the guard cells of the stomata and that of the other epidermal cells when 
the stomata are open. 
(2) That the osmotic concentration in the guard cells increases in the 
early hours of sunshine and decreases in the afternoon, approaching the 
osmotic concentration of the epidermal cells at nightfall. 
(3) That there is very little if any change in the osmotic concentration 
of the epidermal cells during the day. 
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