Stimulation of Root Growth in Cuttings 83 



In addition to the experiment just reported, Ligustrum was used in 

 nine other experiments in which the cuttings were treated with potassium 

 permanganate. In these experiments, some of which are described later 

 in this paper, there were fifty-two treatments with potassium permanganate 

 at different concentrations, usually in duplicate, and for different lengths 

 of time. All these fifty-two treatments, with the exception of three 

 in which the concentrations were too high, showed stimulation of root 

 growth above that obtained in the checks. 



Since Ligustrum was so clearly benefited by the treatment, a few ex- 

 periments were made to determine whether or not other species would 

 be similarly affected. Some of these experiments were started in the 

 latter part of winter, which proved to be too late for successful rooting. 

 Cuttings of Ribes, Cydonia, and Berberis formed roots and the results 

 seemed to indicate some stimulation, but there was such wide variation 

 between duplicate cultures that no definite conclusions could be drawn. 



Treatment with potassium permanganate stimulated root growth in 

 cuttings of a number of woody plants, as is shown in table 3. With 

 several forms the treatment not only resulted in an increase in root length 

 per twig, but also caused a larger proportion of cuttings to take root. The 

 results obtained with Prunus cerasifera are shown in figures 2 and 3. 



All the forms here reported can be fairly readily propagated by 

 hardwood cuttings if these are taken at the proper time of year and if 

 sufficient precautions are used in setting and handling them. It is 

 apparent, however, that if the cuttings are taken late in the season and 

 placed in the sand, with no especial precautions regarding the supply 

 of bottom heat, moisture, light, and temperature, a treatment with 

 potassium permanganate results in a marked improvement in root pro- 

 duction in respect both to the aggregate length and dry weight of the 

 roots of a given twig and to the proportion of twigs forming roots. In 

 addition to the experiments reported in table 3, an experiment with 

 Ligustrum shows very clearly this improvement under adverse con- 

 ditions. Cuttings were taken very late in the season — March 16, 1917. 

 Contrary to the usual practice, the base of each twig was cut square 

 across with rather duU pruning shears and no clean diagonal cut was made 

 with a sharp knife. The twigs were treated as indicated in table 4 and 

 then placed in sand. Because of the lateness of the season and the rather 

 careless treatment, the check twigs failed to develop roots as freely as 



