60 AMERICAN CARNATION CULTURE. 



water — darkness and water close the valves of these breathing 

 plant's mouths. Careful experiments have determined that one 

 superficial foot of leaf surface exhales one and one-fourth ounces 

 of vapor in twelve hours of sunshine. Light lifts the valves and 

 opens the throttles for plant respiration. Darkness, rain and dew 

 closes the pores and maintains merely and equilibrium of plant 



Fig. 2. — Section taken at right angles to the surface through a stoma. The guard- 

 cells, forming the automatic valves, are shown touching each other, so that the stoma 

 passage is closed. The epidermal cells are empty, but the outer wall i.s excessively thick. 



circulation. This is an explanation for not spraying carnations 

 in cloudy weather, in the absence of the drying rays of the sun. 

 Wilted plants are fresh and full of sap after a night of dark- 

 ness and dew, because they have absorbed fluids by the root, and 

 exhaled none in the form of vapor by the leaves. They have 

 been breathless, in a coma, wailing for the sorcery of sun light to 

 stir the magic forces of life into active circulation. 



