EXERCISE 37 



HOW DOES THE AMOUNT OF AVAILABLE STORED FOOD 

 AFFECT GROWTH? 



Materials. Old potatoes. Potato tubers will not sprout readily 

 soon after being dug. If the exercise is performed in the autumn, 

 the tubers to be used should be some that have been stored for some 

 time, preferably in a cold place. 



Directions for work. Cut one of the tubers into two pieces 

 crosswise, split another from end to end, and cut several others 

 into various-sized smaller pieces. Cut several pieces so as to 

 include only one eye and very little food reserve ; cut several 

 others with one eye and as much stored food as possible ; secure 

 several pieces without eyes, and some pieces with several eyes 

 to the piece. It would add exactness to the experiment if the 

 pieces selected for planting were weighed. 



Plant the pieces of tubers in a garden, if the study is made 

 in the spring, or in a box of clean sand in the laboratory. Put 

 a small numbered stick by each piece planted and record in your 

 notebook the descriptions of the pieces. 



Make daily memoranda of the growth of the sprouts as soon 

 as they appear above the soil. When it appears evident that no 

 more will come up, dig up all the pieces planted and lay them 

 in a row on the table for inspection. Tabulate the facts as 

 follows : 



[45] 



