THE RANGE OF DOMINANCE 



153 



stems, each of the same character as the single stem in 

 normal plants, but if one grows more rapidly the growth 

 of the other is usually soon inhibited and only the one 

 continues to develop. If, instead of removing the 

 primary growing tip, we inhibit its metabolic activity 

 in any way without killing it or injuring it otherwise, the 

 result is the same as if it were removed. Inclosure of 

 the primary growing tip in plaster of paris or in an 

 atmosphere of hydrogen accomplishes this result without 

 injury, for it is capable of resuming growth after removal 

 of the plaster or return to air. If the primary tip is 

 inhibited in this way until the axillary shoots have 

 appeared and is then allowed to resume its activity, the 

 growth of the axillary shoots is in turn inhibited and 

 the primary stem continues its development, unless the 

 axillary shoots have attained a length two or three times 

 as great as that of the main stem before the inhibition of 

 the primary tip is removed. In that case the further 

 growth of the primary tip may be almost entirely 

 inhibited by the axillary shoots, and it may even die, 

 while they, or one of them, as the case may be, continue 

 development. Many modifications of the experiment 

 are possible at different stages of development and in 

 different plants. In stems with lateral buds, such as the 

 willow, if the apical growing tip is removed the upper- 

 most lateral bud or buds will develop and their develop- 

 ment inhibits the development of those lower down; 

 if we remove them or prevent their development by 

 inclosing them in plaster, the buds next below will 

 develop, and so on. 



In many plants removal or inhibition of all the 

 growing stem-tips present results in the formation of 



