THE PLANT. 



To enable a plant to flower and bear seed, it would 

 appear necessary in the case of many plants that the 

 activity of the leaves and roots should reach a period of 

 rest. It is only after this that the process of cell-forma- 

 tion seems to gain the ascendancy in a new direction ; 

 and the constructive materials being no longer required 

 for the formation of new leaves and roots, are used to 

 form the flower and the seed. In many plants the 

 want of rain, and the consequent deficiency of incombus- 

 tible nutritive substances, will restrain the formation of 

 leaves and hasten the flowering. Dry, cool weather 

 favours the production of seed. In warm arid moist 

 climates the cereals sown in summer bear little or no 

 seed ; and on a soil poor in ammonia the root-plants 

 more readily flower and bear seed than on a soil rich in 

 that substance. 



If the normal processes of vegetation require a defi- 

 nite proportion of unazotised and azotised materials in 

 the protoplasm which is formed in the plant, it is evi- 

 dent that the want or excess of the mineral substances 

 indispensable for the production of those matters must 

 exercise a very decided influence upon the growth of 

 the plant, and upon the formation of the leaves, roots, 

 and seed. Want of azotised and excess of fixed nutri- 

 tive substances would lead to the formation of unazo- 

 tised materials in preponderating quantity ; but when 

 these have assumed the form of Cleaves and roots, they 

 retain a certain amount of nitrogenous matter, thereby 

 impairing the seed formation, a principal condition of 

 which is an excess of protoplasm. An excess of azotised 

 food, with a deficiency of fixed nutritive substances, will 

 be of no use to the plant itself, because the latter can 

 for its organic operations make use of nitrogenous sub- 

 stances only in proportion as they exist in the proto- 

 plasm, and the contents of the cell are of no value to 

 the plant in the absence of the materials required to 

 form the cell-walls. 



In the process of animal life the organs of the body 

 are constructed from the elements of the egg ; the con- 

 stituent parts of such constructed organs are azotised, 



