AUXIMONES 209 



but in lengthened illumination some long-day plants, e.g. the 

 radish, have more soluble carbohydrate in the shape of sugar 

 and produce flowers. 



From the present aspect the value of these observations 

 lies in the fact that they provide another instance in the in- 

 teraction of the various factors involved in growth : there is 

 no virtue in increasing the one without duly considering the 

 others ; heavy manuring with nitrates, for instance, is mere 

 waste if there be not adequate supplies of water, and adequate 

 and proportionate supplies of both will not promote fruit 

 formation in a greenhouse so dimly illuminated as to depress 

 carbon assimilation. 



AUXIMONES. 



Bottomley * concluded from a large number of experi- 

 ments that something more was requisite for the vigorous 

 growth of a plant than is contained in the ordinary culture 

 solution made up with mineral substances. These promoters 

 of growth, the nature and composition of which are unknown, 

 he termed auximones. Bottomley selected such plants as 

 Lemna, Salvinia and Azolla which normally lead an aquatic 

 existence and thus avoided the rather artificial condition 

 inseparable from the cultivation of a terrestrial plant in an 

 aqueous medium. For healthy growth he found that small 

 amounts of organic matter are necessary : amongst the best 

 results obtained were those in which an aqueous extract of 

 bacterized peat had been added, but other organic substances, 

 such as autoclaved Azotobacter and crude nucleic acid deriva- 

 tives from raw peat, will also serve. 



Bacterized peat is sterilized raw sphagnum peat decomposed 

 by nitrogen fixing bacteria of the soil ; such treated peat is 

 considered to act either as a food substance or indirectly as an 

 accessory food substance. The amount necessary for a posi- 

 tive result is so small that a body comparable to a vitamin is 

 suggested. Thus Rosenheim f found that plants of Primula 



* Bottomley: " Proc. Roy. Soc," B, 1917, 89, 481; "Ann. Bot.," 

 1920, 34, 345, 353. See also article in " The Exploitation of Plants," ed. by 

 F. W. Oliver, London, 1917. Mockeridge : " Proc. Roy. Soc," B, 1917. 

 89, 508. t Rosenheim : " Biochem. Journ.," 191 7, II, 7. 



VOL. II. — 14 



