OBJECTS.] INTRODUCTORY. 83 



in solution, deposit themselves on the crystal in regular 

 order and increase its size without changing its form. 

 And, in this way, the small crystal may grow 

 to a great size. The large crystals of sugar candy, 

 which consist of sugar and water deposited from a 

 strong syrup or saturated solution of sugar, grow in 

 the same fashion, upon threads suspended in the 

 evaporating syrup. In this mode of growth you will 

 observe that the enlargement is effected by addition 

 to the outside of the growing body ; and moreover the 

 matter which is added, namely, the salt or the sugar, 

 already exists as salt in the brine or as sugar in the 

 syrup. 



B. LIVING BODIES. 



56. The Wheat Plant and the substances 

 of which it is composed. 



Every one has seen a cornfield. If you pluck up 

 one of the innumerable wheat plants which are 

 fixed in the soil of the field, about harvest time, you 

 will find that it consists of a stem which ends in a 

 root at one end and an ear at the other, and that 

 blades or leaves are attached to the sides of the 

 stem. The ear contains a multitude of oval grains 

 which are the seeds of the wheat plant. You know 

 that when these seeds are cleared from the husk or 

 bran in which they are enveloped, they are ground 

 into fine powder in mills, and that this powder is the 

 flour of which bread is made. If a handful of flour 

 mixed with a little cold water is tied up in a coarse 

 cloth bag, and the bag is then put into a large vessel 



