32 



tion no doubt would have been observed here if measurements liad 

 been made previous to six hours as is shown in experiments when 

 shorter intervals in the time of measurements were observed. It can 

 be seen, however, from this experiment that retardation and acceler- 

 ation commence to show themselves very early after mutilation. 



The effects of mutilation on growth as shown in the preceding 

 experiments give us some idea of the extent of the shod: produced 

 from this form of stimulation. The tirst effect of mutilation is a 

 disturbance of the normal activities of the plant, which so far as 

 growth is concerned shows itself in a more or less pronounced retar- 

 dation. This is followed by an attempt of the organism to recover, 

 or an accelerated growth. The maximum period of retardation 

 appears shortly after cutting, and the maximum period of accelera- 

 tion at least that obtained from a large number of experiments, would 

 appear to take place in plants making ordinary growth about twenty- 

 four hours after cutting. The degree of retardation and acceleration 

 appears to be more marked in rapidly growing plants, or those that 

 are more plastic, and is especially marked in the less differentiated 

 cryptogams. In some of the lower types of organisms retardation 

 is so brief and acceleration in growth so rapid that very close inter- 

 vals in the time of measurement are necessary to observe the effects 

 of mutilation. 



This series of experiments demonstrates that mutilation causes 

 decided changes in the growth of the organism, and when these 

 mutilations are of a nature not to seriously interfere with the normal 

 condition of the plant, recovery takes place in a few days and the 

 normal functions are restored. The organs nearest the zone of muti- 

 laton show the effects of stimulation, as a rule, in more pronounced 

 degree than those more remote. When pruning is of a certain char- 

 acter, such as shown by the experiments in Tables Xll, XIII and 

 XIV, decided correlations takes place which exerts considerable 

 influence on the configuration of the organism. 



In the latter experiment we have an opportunity to observe the 

 effects which pruning secondary organs has upon the growth of pri- 

 mary organs, and, conversely, the effect that pruning primary organs 

 has upon secondary organs. When pruning of this nature is prac- 

 ticed pronounced results are likely to show themselves. Or, in 

 other words, the pruning of primary organs induces a marked stimu- 



