Fig. '2. — Showing willow cuttings growing 

 in water; those to the right, in ordinary 

 water, those to the left, in water charged 

 with gas. 



FIG. 3. — Showing development of leuticels on 

 willow cuttings growing in water. Figure to 

 the right growing in ordinary water; to the 

 left, in water charged with gas. 



