EXERCISE 109 

 VARIATION IN CULTIVATED PLANTS 



Materials. An exercise similar to the following may be worked 

 out with almost any cultivated or wild plant. Ears of corn are sug- 

 gested as being readily available at any season of the year in most 

 parts of the country. Secure ears of corn from the crib without 

 selection in order that the sample may represent the actual char- 

 acter of the crop as nearly as possible. At least a hundred ears 

 should be included in the study by the class if the number of pupils 

 is great enough to make the study without using excessive time. 

 Popcorn or sweet corn may be used as well as field corn. 



If it is not desired to use corn, other problems may be taken up 

 based upon other plants. The following are suggested : weight of 

 grains in heads of wheat, oats, etc. ; number of heads per plant ; 

 number of grains per head; height of cornstalks; height of corn 

 ears from ground ; height of timothy plants ; number of timothy 

 stems in a clump ; length of timothy heads on different plants ; 

 number of cotton bolls per plant ; weight of cotton per plant ; length 

 of cotton fiber. 



Directions for work. Weigh each ear of corn. Shell the grains 

 off the cob and weigh grains and ear separately. Tabulate as 

 follows and correct any error that appears: 



Weight of entire ear 



Weight of grains only 



Weight of cob only 



Sum of grains and cob 



Error 



Tabulate the weights of grains of all the ears weighed by 

 members of the class in the following blank : 



Number of ears with grains weighing 



Ig.to49g 



50 g. to 99 g 



100 g. to 149 g 



150 g. to 199 g 



200 g. to 249 g 



250 g. to 299 g 



[134] 



