Plant Qrowth'Suhstances 



phenyl-acetic acid) are usually supplied in tubes contaidng 

 one gram (28-4 grams =one ounce avoirdupois). A measure 

 to contain a hundred grams (millilitres) of water can be bought 

 through a druggist, but three and a half ounces of wa:er will 

 be sufficient approximation to a hundred millilitres. 



If the acid, and not a salt, has been obtained, it will be a 

 good plan to dissolve the acid first of all in about five or ten 

 times its weight of alcohol or methylated spirit, which is, 

 however, of no use for the salts. The volume of the solution 

 is then made up with water to the final volume desired for a 

 one per cent, solution. 



The stock solution, when not required, should be stored in 

 a cool, dark place in a bottle of dark-coloured glass, because 

 light tends to decompose the substances. 



From the stock solution a weaker solution can be made 

 freshly as needed, by adding one part of the stock solution to as 

 many parts of water as are desired. Dilutions of about one 

 part of the original substance in one thousand, ten thousand, 

 forty thousand, a hundred thousand, etc., can be made by 

 adding one part of the stock solution to 9, 100, 400, 1,000 

 parts of water respectively. These final dilutions will contain 

 respectively 100, 10, 2-5 and i part of substance per 100,000 of 

 water. No alcohol or other substance except water is required 

 to dilute the stock solution. Tap water is suitable. Any 

 unused weak solution should not be kept, as it will probably 

 become valueless on standing long. 



A smaller measure (to contain 10 millilitres) will be found 

 a convenience both for measuring out the stock solution and 

 for dosing the plants. 



To avoid the trouble of making up solutions from the solid, 

 you may also use commercial preparations. These consist of 

 solutions of a carefully-chosen and efficacious synthetic 

 growth-substance already made up into a stock solution. For 

 use, all you have to do is to follow the simple directions. The 

 size of the bottle you buy is not necessarily an indication of 

 what you are getting for your money, since what may seem 

 dear may be merely more concentrated. 



To the small gardener an advantage of buying one of the 



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