THE NITROGEN COMPOUNDS IN PLANTS 149 



much longer hydrolysis is generally found necessary. The 

 amino acids which have been obtained from the vegetable 

 proteins are the same as those yielded by the animal proteins 

 with the exception of di-amino-trioxy-dodecanic acid. In 

 general, the plant proteins yield more glutaminic acid and 

 ammonia than do the animal proteins. The proteins soluble 

 in alcohol yield the basic amino acids in a very small pro 

 portion, and yield no lysine. The vegetable proteins always 

 contain more nitrogen than the animal proteins. The split- 

 ting products of the cereal proteins are marked by the high 

 proportion of non-basic nitrogen, the low proportion of 

 basic nitrogen, the high proportion of ammoniacal nitrogen, 

 and the small amount of lysine. Glutenin and gliadin, 

 both wheat products, are characterized by the high yield 

 of ammonia in comparison with the glutaminic and aspartic 

 acids present. These proteins must, therefore, contain some 

 nitrogen not occurring in the usual type of amino-acid amide 

 like asparagine. A marked division between the cereal 

 proteins and those of animal origin lies in the fact that the 

 former are completely free from phosphorus. Of course, 

 imperfectly purified specimens will contain some phosphorus 

 adhering to them. A very important correlation is brought 

 out when the character of the proteins in the seeds is compared 

 with the ordinary botanical relationship of the natural 

 orders concerned. The proteins contained in the seeds of 

 the cereals contain a relatively large proportion of those 

 protamins which yield no lysine, muc^. proline, glutaminic 

 acid, and ammonia, with a little arginine and histidine. 

 Hordein, in barley, is characterized by its low percentage of 

 oxygen and large heat of combustion. 



The chief properties and behaviour of the cereal proteins 

 are much alike, and present marked differences from the 

 proteins from other groups of seeds. It is thus found that 

 similar proteins are found only in seeds which are botanically 

 closely related. The embryo in its early periods of growth 

 is fed on special food, but when the plant has reached the 

 stage of finding food from its surroundings, the chemical 

 processes have already become established on fixed lines. 



