AUXIMONES 131 



medium ratio gives moderate vegetative growth and good re- 

 production ; and when the C/N ratio is very low, a vigorous 

 vegetative growth and poor reproduction obtains. Thus the 

 best results occur when these two factors are reasonably 

 balanced. From the present aspect the value of these ob- 

 servations lies in the fact that they provide another instance 

 in the interaction of the various factors involved in growth : 

 there is no virtue in increasing the one without duly consider- 

 ing 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 experiments 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 condi- 

 tion inseparable from the cultivation of a terrestrial plant in an 

 aqueous medium. For healthy growth small amounts of or- 

 ganic 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 derivatives from raw peat, 

 will also serve. 



Bacterized peat is sterilized raw sphagnum peat decom- 

 posed 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 

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

 is suggested. Thus Rosenheim f found that plants of Primula 

 malacoides treated with an aqueous extract of '1 8 gram of 



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

 I 92o, 34, 345, 353. See also article in " The Exploitation of Plants," Ed. by F. 

 W. Oliver, London, 1917. Mockeridge : " Proc. Roy. Soc ," Lond., B., 1917, 89, 

 508. 



f Rosenheim : " Biochem. Journ.," 1917, II, 7. 



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