GENUINE STARCH FACTORIES. 719 



growth of the potato tubers or the plumping out of the grains of 

 corn, wheat, or rice, the same fact remains that storehouses are 

 being filled with the same organic compound. There must be many 

 preliminary steps before this process of storing is complete, and 

 for these we need to seek elsewhere in the growing plant. 



Even the most careless observer can not but be at home with 

 the fact that the whole port and bearing of ordinary plants is for 

 sun exposure. They rise from the ground as closely placed stems 

 of grass or less neighborly orchard or forest trees, and hang out 

 their leaves to catch the sun. The economy of substance is so 

 well studied that there is a very large exposure at a minimum of 

 expenditure of tissue. In short, the leaves are the organs for 

 association wdth the sunlight. They reach toward the sun where 

 light is scanty, as in the window, and even turn their faces to 

 the orb of day, shifting the position hour by hour from sunrise to 

 nightfall. The rapidity with which we come to the fundamental 

 fact that leaves are for the sun almost surprises one. The pur- 

 pose is as easily inferred, but the steps in the process are not so 

 quickly taken. The facts that leaves are yar excellence the starch 

 factories and the sunlight the inobtrusive chemist are granted, and 

 it remains only to show something of the steps of proof that science 

 may have discovered. 



We need, therefore, to consider starch from the standpoint of 

 its composition, and upon this the chemists are fairly well agreed. 

 It consists of three elements, with their atoms so arranged that 

 the molecule of starch has the composition of six parts of carbon, 

 ten of hydrogen, and five of oxygen, or, to express the formula in 

 terse chemical terms, it stands C6II10O5. If we can account for 

 the bringing of these atoms together in the production of a single 

 molecule of starch the laboratory has been explored and the secret 

 is ours, even if we can not put it to practical use in our so-called 

 " starch factories." 



The independent plant, beyond serious question, gets its food 

 from outside itself. There are two sources for these substances — 

 namely, the soil-water bathing the absorbing roots, and the atmos- 

 phere, with which the aerial branches and their leaves are con- 

 stantly surrounded. From the soil come the water and all the 

 salts, ash constituents, and the like that may be dissolved therein, 

 while the gases of the atmosphere bring, among its chief contribu- 

 tions, a constant and, in an always exceedingly diluted form, the 

 carbon dioxide, or, sometimes called, the carbonic-acid gas. This 

 compound, familiar to us as a product of combustion, fermenta- 

 tion, and decay, is composed of carbon and oxygen, and has the 

 symbol CO2 associated with it by chemists. 



