78 R. GREIG-SMITH. 



etc., which are not affected by heat. They may be of the 

 nature of the hop-constituents, which when boiled with 

 water are changed from being petroleum-soluble and pre- 

 servative to petroleum-insoluble and non-preservative. 1 

 They are probably changed into stimulants, for while heat 

 makes a toxic extract nutritive, the nutritive effect is 

 frequently far greater than would be expected from the 

 mere destruction of the toxins. 



The soil toxins have alone been considered, but there is 

 a toxin in the subsoil which differs from that of the soil in 

 remaining toxic upon prolonged boiling. 2 



It is quite within the bounds of possibility that Botham- 

 ley's auximones are altered toxins, for we should expect 

 his process of fermenting organic matter to result in the 

 production of toxins, and the subsequent procedure of 

 evaporating, storing, etc., would be sufficient to alter the 

 toxin into a stimulant. The actual proof that toxins are 

 converted into stimulants by heat however is still lacking. 

 They are undoubtedly weakened, and a stimulating effect is 

 shown which is progressive with the extent of the heating. 3 

 But whether the stimulation is due to a weakened toxin or 

 to a conversion of the toxin into an auximone is not at 

 present known. The proof will probably be furnished 

 indirectly by showing that a solution of Bothamley's auxi- 

 mones is toxic before treatment, or that its nutritive or 

 stimulating effect is altered by heat. 



The Commercial Use of Partial Sterilisation.* 



The partial sterilisation of soils has been used on a com- 

 mercial scale in England for glass-house work in which the 

 soils consist of compost, virgin loam, straw-manure or 



1 Chapman, Proc. Chem. Soc, 29 (417) 182. 



8 Proc. Linn. Soc, New South Wales, 1913, 725. 3 Ibid., 1910, 808. 

 1 Eussell and Petherbridge, Journ. Board Agric., 18, 809; 19, 809. 

 Russell, ibid., 21, 97. 



