CHEMISTRY AND USES OF THE POTATOE. 19 



(66.) Starch exists in the plant in the form of rounded, 

 elliptical, or polyhaedral granules, each of which has a lit- 

 tle spot called the hylum, by which it is supposed to be 

 attached to the cell of the plant. (Plate v., fig. 5, Plate 

 vii., fig. 8.) The starch granules consist of concentric 

 rings or rugae, similar to those which starch cells present 

 on their surface. Potatoe starch consists of carbon 44'25, 

 water 55-75. The quantity of starch differs in different 

 months, and the size of the granules varies from the 40^0 

 to the 3 J, of an inch. 



Ibs. 



In August, about . . 10 

 In September . . . 14j 

 In October . . . 14| 

 In November . .17 



Ibs. 



In March . . . .17 

 In April 13f 



In May . . . .10 



(67.) I am not aware that any good analysis of potatoe 

 albumen has been published ; but from analogy we may 

 suppose that it consists of carbon, hydrogen, nitrogen, and 

 oxygen. It exists in the potatoe plant in a state of solu- 

 tion, and separates spontaneously by coagulation from the 

 expressed juice. 



(68.) Regarding the potatoe in a more chemical manner, 

 we find that, according to Boussingault and Bsechmann, it 

 is composed of the following ultimate elements : 



Boussingault. Bicchmann. 



Carbon . . 44-1 . . 43 944 



Hydrogen . 5'8 . . 6 -222 



Nitrogen Oxygen . 45*1 . . 44919 



Ashes . 5*0 4-915 



100-0 lOO'OOO 



(69.) Gerard says " that the temperature and vertues 

 be referred unto the common potatoe (meaning thereby 



