Plant Qrowth'Suhstances 



II. The loam and ballast are sterilized together, and the 

 sand separately. The unsterilized moss-peat is added after- 

 wards, with the following per bushel of compost: il ounces 

 hoof and horn ; 1 2 ounces superphosphate ; I ounce sulphate 

 of potash ; i ounce pure chalk. The fertilizers must have been 

 finely ground, and all must be mixed thoroughly. 



Further information about composts is given in the book 

 by the same authors (Lawrence and Newell) : Seed and 

 Potting Composts, with Special Reference to Soil Sterilization 

 (London: George Allen & Unwin, 1939. 3s. 6d.). 



Note 



American readers in particular should note that the treat- 

 ment of cuttings with indole-acetic acid, indole-butyric acid, 

 indole-propionic acid, and naphthalene-acetic acids (and 

 salts and esters of these) is covered by U.S. Patents respec- 

 tively numbered 2,129,598; 2,129,599; 2,129,601; and 

 2,129,600; these were granted in September 1938, and were 

 taken out by A. E. Hitchcock and P. W. Zimmerman on 

 behalf of the Boyce Thompson Research Foundation of 

 Yonkers, N.Y. 



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