110 Otis F. Curtis 



Calcium chloride and sodium acid phosphate, the one alternating with 

 the other, followed in order of growth, while the check cultures in tap 

 and distilled water were last, excepting those solutions that were dis- 

 tinctly toxic. Potassium permanganate was strongly toxic at the con- 

 centrations used. The weakest solution of ferric chloride alone showed 

 marked stimulation. Apparently distilled water also was toxic, as the 

 roots of the cuttings were stunted and produced short, thick branches. 

 It is interesting to note that a supposedly toxic substance, such as boric 

 acid, so markedly stimulates growth when alone in distilled water, espe- 

 cially when the latter itself is toxic. 



In another experiment in which Iresine cuttings were placed in solu- 

 tions of boric acid and ferric chloride, the latter caused greatly increased 

 root growth while the former showed little or no effect. 



Experiments with woody cuttings 



Continuous treatment. — Cuttings of Ligustrum were placed at different 

 times in various concentrations of the following compounds: FeCls, 

 Fe2(S04)3, MnS04, MnOj, H3BO3, H3PO4, NaHaPO*, CaCU, AljCle. 

 The results in some cases were rather irregular. Manganese sulfate 

 was usually toxic in these continuous treatments, but only a few con- 

 centrations were tried. Manganese dioxide showed stimulation in three 

 experiments, had little effect in two, while in a sixth retardation was 

 evident. Iron, either as FeCls or Fe2(S04)3, clearly showed stimulation 

 in each of the three experiments in which it was used. Boric acid (H3BO3) 

 indicated stimulation in two experiments, but in a third showed slight 

 retardation. .Phosphoric acid (H3PO4) caused stimulation in one experi- 

 ment and injury in another. Aluminium chloride (AUCle) showed stimu- 

 lation in the two experiments in which it was used. Some of the results 

 obtained are recorded in table 10 (pages 106-7). 



Liimited treatment. — Cuttings were treated for twenty hours as indicated 

 in table 11. One lot was then placed in sand and another in distilled 

 water. The cuttings in distilled water were kept at a temperature about 

 six degrees (centigrade) lower than the others, which accounts for their 

 slower growth. The results of the limited treatment show a marked 

 stimulation with permanganate and manganese sulfate, as regards both 

 roots and tops. In the cuttings subsequently placed in sand, the boric- 

 acid and hydrogen-peroxide treatments retarded growth. 



