492 Prof. W. B. Bottomley. Effects of Auximones on 



unity, and calculating the corresponding figures for each of the other series. 

 The figures thus obtained are given below. 



Table VI. 





Comparative rate of doubling 



Units of time required to 





in a 



given time. 



double. 





Series. 













No. 



wt. 



No. 



Wt. 



I 



1-0 



1 -o 



100 



100 



II 



2-05 



3-09 



48 



32 



III 



1 -91 



2 71 



52 



37 





1 -63 



2 -01 



61 



50 



V 



1 -24 



1 -48 



80 



67 



Very little difference was noticed in the appearance of the plants in the 

 various dishes for the first week, but during the second week the effect of the 

 auximones became apparent, especially in Series II and III, although it was not 

 until the third week that the effect in Series IV and V became well marked. 

 The plants* in Detmer's solution gradually assumed a starved appearance 

 which became very marked as the experiment progressed. They gradually 

 lost their green colour, and after the third week their decrease in size was 

 very noticeable. The auximone effect was shown by increased rapidity of 

 multiplication of the plants, larger size, stronger root development and greener 

 colour ; that is, essentially, by a more vigorous and healthy growth. 



It is clearly evident from the results obtained in the various series that 

 successive fractionation of the extracts obtained from bacterised peat resulted 

 in a diminution of the effective growth-promoting substances present. The 

 best results were shown in Series II, where the whole of the water-soluble 

 substances were supplied, while in Series III, where soluble humate was 

 eliminated from this water extract, growth was not so good. This may have 

 been due partly to the absence of soluble humate as such and partly to the 

 removal of certain organic substances adsorbed in the precipitated calcium 

 humate. Again, in Series IV, the elimination of all except the alcohol-soluble 

 substances resulted in a much less marked, though still very appreciable, 

 effect ; and this was still further emphasised in Series V, where the decomposed 

 phosphotungstic-acid fraction was employed. These facts are brought out in 

 the following diagram, in which the five verticals are drawn to represent the 

 five series shown in Table III. The total mean number and weight of the 

 plants in Series I at the end of six weeks are taken to represent unity, 

 and this is marked off on the first ordinate, the corresponding numbers for the 

 other series being calculated, both for weight and number, and marked off on 



