NUTRIENT SOLUTION FOR PLANTS. 157 



well's former usefulness was restored. Set pupils inquiring 

 about and observing the work done by plant roots. 



The growth of potato steins in a cellar illustrates how the 

 plant strives to reach the light. 



Setting a freshly-cut stem in water colored with red ink or 

 aniline blue for a few hours will enable one to trace the paths 

 taken by the raw fluids that enter a plant. Balsam or 

 nasturtium stems are suited to this experiment. Cut off a 

 thin willow branch ; two or three inches from the lower end 

 carefully girdle a ring a half inch wide without cutting the 

 wood. Set it in water that does not reach the girdling. 

 Note how long the leaves remain fresh. Similarly girdle 

 another willow twig and keep it, the girdling being immersed, 

 with a third ungirdled twig in water. Note where roots begin 

 to grow in each case. Infer that the raw fluids traverse the 

 wood and the digested fluids the bark. 



Nutrient Solution for Plants.— All solid plant food 



must be dissolved before it can be absorbed. By analysis, the 

 elements of the substances that green plants require for food 

 have been discovered. The experiments made by Sachs led to 

 his discovering that if the following quantities of the substances 

 named are dissolved in a gallon of water, the solution will 

 nourish plants from germination to flower, or in some cases to 

 fruit : One-twelfth of an ounce of each of — table salt, NaCl ; 

 phosphate of lime, Ca 3 (P0 4 ) 2 ; gypsum, CaS0 4 ; Epsom salts, 

 MgS0 4 ; one-sixth of an ounce of saltpetre, KN0 3 ; a bit of 

 chloride of iron about the size of a small pea. If you have 

 not the means of weighing a smaller quantity than a quarter 

 of an ounce, either divide it by inspection into three equal 

 parts, or make up three gallons of the solution. Plants may 

 be grown in this solution, changed occasionally as it weakens, 

 supported on a piece of muslin tied over a tumbler or in 

 sawdust, or clean sand, or sponge regularly watered with the 



