IIO THE FIRST BOOK OF FARMING 



dissolved plant food up through the stems to the 

 leaves. There most of the water is passed from the 

 leaves to the air and is condensed on the sides of 

 the glass. A work of leaves then is to throw off or 

 to transpire moisture and thus make room for a 

 new supply of food-laden moisture. This water is 

 thrown off through little pores or mouths or stomata 

 which are very small and very numerous on the 

 under side of the leaf. It will be noticed that the 

 plant not placed in the sunlight transpires very lit- 

 tle moisture, showing that sunlight helps the leaves 

 in this work of transpiration. 



How much water does a plant transpire or throw 

 off from its leaves? 



Experiment. (See Fig. 60). Fill a common 

 quart fruit jar or can with soil and plant in it a 

 kernel of corn, a bean, a cotton seed or seed of some 

 other plant. After the plant has grown to be twelve 

 or fifteen inches high, cut a piece of pasteboard a 

 little larger than the top of the jar, cut a hole in 

 the centre as large as the stem of the plant and make 

 a slit from edge to centre. Soak the pasteboard in 

 melted wax or paraffine candle. Cool it and then 

 place it over the jar, slipping it around the plant 

 stem. Now solder the pasteboard to the jar with 

 melted candle making the joints tight all the way 

 around. Then close up the slit and the hole about 

 the stem. The jar is now completely sealed and 

 there is no way for water to escape except through 

 the plant. The plant should be well watered before 

 the jar is closed. Now weigh the jar and set in the 



