Rooting of Cuttings 



prejsion that the roots produced on cuttings after a treatment 

 with indole-butyric acid are more desirable in type than those 

 produced by the naphthyl compound at least ; in other words, 

 indole-butyric acid scores on quality. 



There is one artificial growth-substance which is almost 

 ridiculously cheap, costing only a few pennies an ounce. 

 This is p\ienyl-acetic acid. It is, however, much less potent 

 than the o'-.hers that have been mentioned. It often requires 

 to be used at about ten times the strength at which the 

 other substances are used, and even so it produces good root- 

 ing with relatively few species. In Dr. Tincker's experiments 

 only about 1 5 per cent, of species rooted after treatment with 

 phenyl-acetic acid solutions, and as those which rooted were 

 mostly species easy to root, the figure of 15 per cent, compared 

 with about 50 per cent, for the other substances probably 

 flatters phenyl-acetic acid. It has its special advantages, 

 nevertheless, and there is no reason why it should not be 

 tried. It has a delightful rose smell, and if you give it up as a 

 growth-substance you may like to use it to freshen pot-pourri 

 or for other fragrant purposes. 



None of these substances, which are called acids for 

 reasons of theoretical chemistry, is corrosive in the ordinary 

 sense. They are all powders, practically bland. They dissolve 

 only to a minute extent in water, though phenyl-acetic acid is 

 soluble enough in water to give a rose odour to a clear (filtered) 

 solution. Compounds of the acids with potash and other bases 

 {e.g., soda, lime) are called salts; they have been used by 

 experimenters, because some of them have the advantage of 

 being appreciably soluble in water. These useful salts are not 

 widely available in the solid form. 



How to Prepare 



Only very low concentrations of the chosen substance are 

 necessary. As it is difficult to make a very dilute solution 

 straight away, the best way is to make, say, about a one per cent, 

 "stock" solution of the substance in water, by dissolving a 

 known weight of the substance in a hundred times its weight 

 of water. The dearer substances (that is, all of them except 



13 



