OFFICE OF STOMATA 173 
often found per square inch on the under side of the 
leaves of ordinary cultivated plants. The stomata 
Fie. 41. Diagram of open and partly closed breathing-pores on leaves. 
Through these openings water escapes from the plant. (From King’s 
“Trrigation and Drainage.’’) 
or breathing-pores are so constructed that they may 
open and close very 
readily. In wilted 
leaves they are prac- 
tically closed; often 
they also close im- 
mediately after a 
rain; but in strong 
sunlight they are 
usually wide open. 
It is through the 
stomata that the 
gases of the air enter 
the plant through Fia. 42. Photograph of stomata or breath- 
which the discarded ing-pores on under side of leaf. 
oxygen returns to the atmosphere. 
It is also through the stomata that the water which 
