The Plant. 103 



a greater or less extent precursors of protein compounds in the 

 new seed. Being readily soluble in water, they form ready 

 means for the transportation in the sap of protein forming struc- 

 tures, and can be placed at the disposal of the reconstructive 

 forces in the plant. 



Amines, or compound ammonias, have only a limited practical 

 importance as plant compounds. They are strongly basic com- 

 pounds resulting from the replacement of hydrogen in ammonia 

 by hydrocarbon radicles. The rank odor of some plants as the 

 fetid goose foot and hawthorn is due to compounds of this sort. 



Alkaloids are basic organic compounds involving substitution 

 of more complex organic radicles into the ammonia molecule than 

 is the case with the amines. By virtue of their basic structure 

 they combine with acids ; the salts so formed offer means of iso- 

 lating and purifying these bodies. Some of the more common 

 alkaloids are nicotine of tobacco ; morphine of the poppy ; strych- 

 nine, brucine and curarine of strychnos wood ; quinine of cinch- 

 ona bark; piperin of pepper; solanin of the potato and night- 

 shade; and cocaine of the leaves of the South American cocoa 

 tree. Some are of medicinal value as stimulants (strychnine), 

 others act as narcotics (nicotine, morphine), and still others are 

 virulent poisons (curarine, solanin). Curarine is the active con- 

 stituent of curare extract with which some wild tribes poison 

 their arrow-tips. 



The ash constituents of the plant, usually relatively small in 

 amount, are for the most part absolutely essential to its life 

 activities. The following chemical elements are always found in 

 plant ash: Calcium, potassium, magnesium, sodium, iron, phos- 

 phorus, sulphur, chlorine and silicon. Manganese and aluminum 

 are occasionally present ; and zinc, barium and other metals some- 

 times occur as accidental constituents. 



The following brief table gives the amount and composition of 

 the ash of some typical plants. The subject will be taken up 

 more in detail in connection with the relative composition and 

 food demands of crops. 



