CH. II] 



STARCH. 



27 



that used by washerwomen. In the laboratory it supplies 

 a material for the microscopic study of starch. A section 



Fm. 9. 



YOUNG BKANCH OF IVY, 



showing adventitious roots. 



From Le Maout and Decaisne. 



through the flesh of the potato shows the following things: 

 on the outside is a layer of cells arranged in a regular 

 manner like bricks one over the other. These form a layer 

 of cork serving as a protective layer on the surface ; it will 

 not be necessary to consider it in any detail, but it should 

 be noted that it is beneath the corky layer that the starch 

 is found. The main body of the tuber is made up of paren- 

 chyma, a tissue of simple cells fitting together like bees' 



