Plant Qrowth'Suhstances 



compost, suitably labelled. At the end of 24 hours withdraw 

 half the remainder and plant them out, and withdraw the last 

 lot at from 36 to 72 hours after the beginning, and plant out. 

 You will have thus nine lots of cuttings, which have been 

 subjected to three concentrations for three periods of time. 

 Concentration of the growth-substance and length of exposure 

 thereto have often to be narrowly judged, but there is a 

 certain latitude — just as in exposing a photographic negative 

 — and at least one lot of your cuttings should have received 

 something like the proper treatment from the suggested 

 ranges of concentrations and times. It would add to the 

 interest if you planted out a few cuttings treated with water 

 only. 



If phenyl-acetic acid is used, all the above-mentioned 

 concentrations might be increased about ten times. That is, 

 the amounts of water mentioned should be added to say 100 

 millilitres (3^ ounces) of stock solution, instead of to 10 milli- 

 litres. 



After removal from the solutions the cuttings look just the 

 same as before. All that has happened is that transpiration 

 of water through the leaves has occurred, and some of the 

 solution has been sucked up. Visible roots will not be pro- 

 duced before at least a couple of weeks in compost. The time 

 will depend upon the season of the year, as well as on the kind 

 of plant. 



Experience has shown that immersion for 12 or 24 hours in 

 a solution of about 5 to 10 parts of growth-substance per 

 100,000 of water is about right for several kinds of plants, and 

 this may serve as a rough guide if you are not willing to experi- 

 ment with several concentrations and times as I have sug- 

 gested. Immersion in a relatively strong solution for a short 

 time (say 10 parts per 100,000 overnight) seems to be usually 

 better than immersion for a longer time in a weaker solution. 

 On the other hand, an error in judgment of the concentration of 

 a "strong" solution may lead to the preparation of a solution 

 that is poisonous to the cuttings. Be prepared for disappoint- 

 ments ; for death of cuttings left too long in the solutions, or in 

 too strong a solution; and for no results, from insufficient 



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