76 Otis F. Curtis 



chiefly the moisture, temperature, and light relations, as well as the effect 

 of the time and manner of making the cuttings. Some of those practices, 

 however, have been briefly discussed in the latter part of this paper, in 

 so far as they are related to the present investigation. 



In the experiments conducted by the writer, the cuttings, taken under 

 different conditions as stated for each experiment, were subjected either 

 to a limited or to a continuous treatment with the various compounds 

 used. For limited treatment the time ranged for the most part from 

 one to two days. The cuttings were then rinsed and placed in flasks 

 or in sand. For continuous treatment the cuttings were placed in 

 flasks containing the various compounds dissolved in distilled water, 

 tap water, or full nutrient solution. A few tests were made in which 

 the compounds were applied to sand in pots or flats. and the cuttings 

 were placed directly in these, but no very decided results have thus far 

 been obtained. 



For the limited treatments 10.0 cubic centimeters of solution was 

 used unless otherwise stated. These treatments were administered 

 either in tall glass cylinders, in large test tubes, in flasks, or in tumblers. 

 The cuttings that were left in liquid media were placed in Erlenmeyer 

 flasks of resistance glass, 250 cubic centimeters in capacity. The flasks 

 were carefully cleaned and then covered with black paper. In the 

 majority of cases ten twigs were placed in each container, and the con- 

 tainers were set in trays on benches in the greenhouse. No special pre- 

 cautions were taken for controlling the temperature and the relative 

 humidity. The cuttings in sand were on a greenhouse bench with no 

 bottom heat. 



In comparing the relative values of the several treatments, the average 

 total root length per twig was taken as the best criterion. The number 

 of roots and the average length of the individual roots were also 

 determined in some cases, but these figures were not consistent. For 

 example, in a given culture one twig might have a large number of short 

 roots while another had a small number of long roots, and therefore, 

 according to the number of roots, the two would be quite distinctive. 

 The total root length per twig, however, proved to be fairly constant. 

 The total green and dry weights per culture were determined in a few 

 instances. 



