162 NATUEE STUDY 



or, better, two months, remove the marble. On its sur- 

 face will be found the markings of the roots. These have 

 dissolved the marble by means of an acid of their own 

 manufacture. 



Seed Food-supply: 



It is, perhaps, an open question how much of the work 

 in plant physiology above given should be taught. Omit 

 all of it, rather than not give some lessons on seed food- 

 supply. 



Facts : 



Either wrapped around the embryo, or stored away in 

 some of its parts, is food sufficient to supply the needs 

 of the body plant until it is able to get and make food 

 for itself. This may be in the form of starch, oil, pro- 

 teids, such as the gluten of wheat, or cellulose, of which 

 the hard seed of the date is an example. 



Iodine turns wet starch blue or black ; oil is easily de- 

 termined by the stain that it makes on paper. The 

 gluten of wheat may be extracted by chewing it until 

 only the gummy gluten is left. Many seeds — the nut- 

 meg, for example — contain several kinds of food. 



Method : 



Give the children peanuts. Where do they grow? 

 On what part of the plant are they found ? Do the flow- 

 ers which produce them bloom under the ground, too ? 

 Why is this ? 



How many coats has the peanut? How many parts 

 to the seed ? Look closely. Do you find anything con- 

 necting these parts ? What is it ? 



Prick the nut. What happens ? Of what use is the 

 oil to the seed? Do you know of any people who like 



