180 



HEREDITY AND VARIATION 



hundred apples, sell $1.75 per hundred, continue bearing thirty 

 years. 



(3) Trees 25 feet apart, bear after six years, produce four hun- 

 dred and fifty apples per tree, continue bearing forty years, price 

 $2.25 per hundred. 



(4) Trees 18 feet apart, bear after five years, average three 

 hundred and fifty apples per tree, bear for twenty years, average 

 price $3 per hundred. 



(5) Trees 30 feet apart, bear after six years, average six hun- 

 dred and fifty apples per tree, continue bearing twenty-five years, 

 average price $2 per hundred. 



(6) Trees 24 feet apart, bear after six years, average five hun- 

 dred apples, bearing thirty years, average price $3.25 per hundred. 



(7) Trees 20 feet apart, bear after four years, average two hun- 

 dred and fifty apples per tree, continue bearing thirty years, price 

 per hundred $3.75. 



Conclusion. — Which of the above would you choose to grow 

 in the area? Give your reasons. 



Problem 157 : How hyhridization is accomplished in flower- 

 ing plants. 



Materials. — Plants in flower, manila bags, camel's-hair brush. 



Method. — Tie a manila bag over a growing apple or pear bud (or 

 any other large available flower) that is about to open. Remove 



from another flower of the same family, but 

 another species, all parts except the pistil, be- 

 fore the flower opens. Cut at fine marked 

 W on figure. Tie a bag over it also. 



When the flower in the first bag opens, 

 transfer some of the pollen to the stigma of 

 the flower without stamens. This may be 

 done by means of a small camel's-hair brush. 

 Cover the surface of the stigma with pollen. 

 Label the stigma thus pollinated, stating the 

 date, and all data concerning source of 

 pollen, etc. 



Observations. — Why do we cover the 



