Stimulation of Root Growth in Cuttings 127 



that these twigs may live and may produce better roots than will un- 

 treated twigs. If maturer twigs are used, however, the increase in root 

 growth is not so great and growth may even be retarded, especially if 

 the twigs are placed in water instead of in sand. With these maturer 

 twigs there is usually an increased top growth, and the treatment also 

 determines to a certain extent the node at which the strongest shoot 

 development will occur. Normally the buds at the uppermost nodes 

 develop the strongest shoots, but in twigs treated with sugar the buds 

 lower down are more likely to develop. Even in twigs placed in narrow- 

 necked flasks so that only the uppermost buds were exposed to the Ught, 

 the lower, darkened buds developed. 



Two possible explanations for this unusual development have occurred 

 to the writer. The sugar may increase the concentration within the 

 cells in the lower part of the stem, and this increased concentration and 

 osmotic pressure may reduce the water content of the upper part; in 

 practically all cases the upper part becomes withered and shrunken, but 

 this withering is not evident until some time after the shoots are formed. 

 On the other hand, the presence of sugar near the base may increase the 

 available supply of organic matter for the lower buds, which may therefore 

 grow earlier and more rapidly than the upper buds; this increased growth 

 might result in the loss of both food and water from the upper part. 



Howard (1915 b) reports that after the freezing of twigs the basal 

 buds are more likely to develop than are the terminal buds. He found 

 also that mechanical injury near or just below a bud results in the develop- 

 ment of that bud. Furthermore, he has shown that mechanical injury 

 increases the ^gar content of a twig. In this respect the condition is 

 similar to the sugar treatment here reported. But other conditions do 

 not closely correspond, as the buds of the twigs treated with sugar were 

 not in the resting condition as were those in Howard's experiments. 

 Moreover, the mechanical injury may have increased the permeabihty, 

 allowing for a loss of carbon dioxide and an increased supply of oxygen. 

 The writer has found that if a twig which has passed the rest period is 

 coated with paraffin, any bud, irrespective of its position, can be induced 

 to develop while all the others remain dormant. This can be done by 

 cutting the paraffin coating in such a way as to aUow for aeration. The 

 bud development cannot be explained as resulting from a mechanical 

 weakening of the coat, for the surest way to induce development is to 



