86 EXPERIMENTAX. PLANT PHYSIOLOGY 



Experiment 54 



Aim. — To determine the nature of the food that is 

 stored in the cotyledons of the French bean. 



Fig. 40 



Method. — Break a cotyledon across and place the cut 

 end in iodine solution. 



Observation. — The broken end of the cotyledon turns 

 blue. 



Inference. — Starch is stored in the cotyledons of the 

 French-bean. 



The food-store in all seeds is not in the form of 

 starch. Oils and fats are sometimes stored in seeds; 

 and, in other cases, the store consists of proteins, sub- 

 stances which resemble the white of egg. 



