THE VOLATILE PAET OF PLANTS. 119 



temporarily accumulate in seedlings and buds, but disap- 

 pear again as growth takes place, being converted into 

 albuminoids, in which transformation they require the 

 conjunction of carbhydrates. Their ability to unite with 

 acid as well as bases further qualifies them to take part 

 in these physiological processes. 



The imides are also at once weak bases and weak acids. 

 , Uric acid and allantoin, relatively rich in oxygen, have 

 the acid qualities best developed. Guanin and cafEein, 

 with less oxygen and more hydrogen, are commonly 

 classed among the organic bases, as in them the basic 

 characters are most evident. 



Amines. — When the hydrogen of ammonia is replaced 

 by hydrocarbon groups (radicals) such as Methyl, CHs, 

 Ethyl, CsHs, Phenyl, CeHj, etc., compound ammonias or 

 amines result which often resemble ammonia in physical 

 and chemical characters, and some of them appear to be 

 stronger bases than ammonia, being able to displace the 

 latter from its combinations. 



Trimethylamine, N(CH8)8, may be regarded as ammo- 

 nia whose hydrogens are all substituted by the methyl 

 group, CHs, and is a very volatile liquid having a rank, 

 fishy odor, which may be obtained from herring pickle, and 

 exhales from some plants> as from the foliage of Chenopo- 

 dium vulvaria, and the flowers of Crataegus oxycantha. 

 It is produced tromrbetain (trimethylamidoacetic acid), 

 by heating with potash solution, just as ammonia is 

 formed from many amides under similar treatment. 



Cholin, C5H15NO2, and Neurin, C5H13NO, are organic 

 bases related to trimethylamine, which were first ob- 

 tained from the animal. Cholin is an ingredient of the 

 bile, and is found also in the brain and yolk of eggs, 

 where it exists as a component of lecithin. It has latterly 

 been discovered in the hop, lupin and pumpkin plants, 

 and in cotton seed ; by oxidation it yields betain. Neu- 

 rin is readily formed from cholin by the action of alka- 



