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



thought possible that some of the beneficial effects of the added organic 

 matter in the previous experiments might be due to a neutralisation of the 

 toxicity of the distilled water used. 



Owing to the limited supply of glass-distilled or " conductivity " water 

 available, it was impossible to duplicate the whole of the series, but for the 

 purpose of testing how far the diminution in size and vigour of the plants 

 grown in ordinary distilled water, in Series I of the previous experiment, was 

 due to any toxicity of this water, an additional series of ten dishes, precisely 

 similar to Series I, except for the fact that conductivity water was used 

 instead of the ordinary distilled water, was prepared, and this ran con- 

 currently with the rest of the series. This set was numbered from 51 to 60, 

 and was known as Series VI. 



The fact that these plants multiplied more rapidly and retained their 

 green colour longer than those in Series I indicated that this water was less 

 toxic than the ordinary distilled water. By the third week, however, when 

 the first halving of the whole set was 'made, the diminution in size of these 

 plants was very marked. It was therefore decided that, instead of estimating 

 the dry weight of one-half of the plants in each dish in this series at this 

 stage, these plants should be used for testing the effect in conductivity water 

 of certain auximones. As only sufficient conductivity water was available 

 for another ten dishes, and it was desirable that two of the auximone 

 fractions should be tested, two small series, each consisting of five dishes 

 only, were employed. This reduction in the number of the dishes in the 

 new sets appeared to be justified at this stage by the uniformity in the 

 number of plants which prevailed throughout the whole of the dishes in any 

 one series, of the above experiment. 



The halves of dishes 51 to 55 respectively were transferred to dishes 

 numbered 61 to 65, containing a solution similar to that used in Series III, 

 but made up in conductivity water. This set formed Series VII. Similarly, 

 the halves of dishes numbered 56 to 60 formed another series containing an 

 alcoholic extract of bacterised peat as in Series IV. Unfortunately, the 

 plants in this series very soon became attacked by a fungal disease, and 

 were eventually discarded. At the 7th week of the experiment this series 

 was replaced by another consisting of the halves of the contents of dishes 

 56 to 60 at this date. This set was numbered from 66 to 70 and formed 

 Series VIII, containing a culture solution similar to that in Series II, made 

 up in conductivity water. The peat extract used here, however, was reduced 

 to half strength, the extract from 1 grm. being used in every 1000 c.c.,. 

 instead of 500 c.c. as in Series II. This represented a concentration of 

 184 parts per million of organic matter. These series in conductivity water 



