144 THE FLORIST AND 



not too far advanced, the flowering, suspended for a while, is resumed, but 

 all the flowers are sterile. 



If we make the experiment upon a cereal whose hollow stem does not ad- 

 mit of the production of new branches, the course of the phenomenon, the 

 growth of the stem, crowned with its spike, is arrested, and from the neck of 

 the root there spring up clusters of stalks which soon overtop the parent 

 stem. In this case also the plant bears no fruit. 



All these phenomena may be satisfactorily referred to the general laws of 

 physiology. In truth all organized beings are subject to a law of compensa- 

 tion which maintains harmony between the functions, and controls the de- 

 velopment of the organs. Whenever any organ receives an undue develop- 

 ment it is at the expense of some other organ, and if a function exerts too 

 much activity, it is always at the expense of some other function. If the or- 

 gans of growth, that is to say the stem, the branches and the leaves are de- 

 veloped beyond a certain limit, it is at the expense of the organs of repro- 

 duction; the flowers are sterile and the plant bears no fruit. In the experi- 

 ments above described, the plant was at the moment of flowering exposed to 

 the action of ammoniacal vapor — its influence determined the formation of a 

 certain number of leaves. This sudden formation of new leaves destroyed the 

 equilibrium between the functions of growth and those of reproduction, and 

 caused the former to predominate over the latter. 



The action of ammonia does not operate with the same energy in all the 

 stages of the growth of plants. The effects are more marked from the time 

 of germination to that of flowering than from this last period to the ripening 

 of the fruit. This difference is easily understood. Up to the time of flow- 

 ering all the activity of the plant resides in the foliaceous organs ; favorable 

 influences determine the formation of an increased number of leaves, which, 

 being the organs of absorption, add their effect to the cause which has given 

 them birth. After the flowering on the contrary, all the activity of the plant 

 is turned to the organs of reproduction. Part of the leaves wither and fade, 

 and those which remain are far from being as large as the first ; the result is 

 that the surface of absorption is diminished. Furthermore, at this stage the 

 plant is near the extreme limit of its development. These two considerations 

 enable us easily to account for the less marked effects that ammonia produces 

 during the second period of the life of plants. 



The use of ammonia cannot fail to become common in greenhouses. In an 

 experiment where it was introduced into a greenhouse of Orchideae it was 

 found to impart an extraordinary activity to their growth. The results ob- 

 tained under these new conditions are so striking that the practical ques- 

 tion may be regarded as settled. 





