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lus to secondary organs, and, conversely, the pruning of secondary 

 organs induces marked changes in the growth of primary organs. 



In the splitting of roots the injuries were of an insignificant char- 

 acter, and no very serious consequences of a permanent nature were 

 likely to follow, since in this case none of the organs were removed 

 and the nature of the mutilation did not affect the morphological 

 balance of the organism. 



In the destruction of the leaders of any terminal organ we 

 seriously interfere with the normal geotropic irritability of the organ- 

 ism, and mutilations of this character are sufficient to induce quick 

 and decided response. The degree of irritability or response to 

 stimulation is more marked in secondary organs when the primar}' 

 organs are cut, and vice versa. This appears to be a marked case 

 of specific irritability, as we have a particular type of stimulation 

 producing tolerably definite results. 



In conclusion, it may be stated that mutilation acts as a severe 

 shock and sets the self-regulatory functions of the organism into activ- 

 ity, inducing a series of changes and responses which manifest them- 

 selves according to the nature, degree of intensity and method of 

 applying the stimulus, and they are also dependent upon the nature 

 of the organism stimulated. 



GENERAL CONSIDERATIONS IN REGARD TO PRUNING. 



One of the fundamental requirements of pruning consists in the 

 ability or power of the organism to respond to stimuli. In plants as 

 well as animals, stimulation and response go hand in hand and the 

 manner of responding or reacting on the part of the organism 

 depends upon the nature, degree of intensity and method of apply- 

 ing the excitory cause or stimulus, and also upon the nature of the 

 organ stimulated. The responses of organisms to stimuli are mani- 

 fold and specific. Every cell, tissue and organ of the plant presents 

 tolerably definite relations to every other, and these are suited or 

 accommodated to the requirements of the organism. Whenever the 

 component parts of a plant are stimulated or its normal functions are 

 interrupted in any way the organism undergoes modifications. If 

 the stimulus or excitory cause is of a certain definite nature charac- 

 teristic response follows, although different stimuli may give rise to 



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