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



demonstration. They grow rapidly, and their increase being principally in 

 one plane is easily noticed at a glance. Moreover a rough numerical estimate 

 of the amount of increase in a given time can be made by counting the 

 fronds." 



A preliminary experiment with Lemna minor .growing in water culture 

 solutions showed that this plant responds readily to the presence of 

 auximones, and, when supplied with these substances, there is strong and 

 healthy growth for an indefinite period. Also by counting the number and 

 measuring the areas of the fronds at regular intervals of time when growing 

 in different culture solutions, a reliable estimate of variations of growth can 

 be obtained. 



Accordingly a detailed investigation of the influence of certain auximones 

 on the growth of Lemna minor was commenced. On July 1, 1915, three 

 similar porcelain dishes of 1 litre capacity were prepared : one containing 

 600 c.c. of Detmer's complete culture solution made up with glass-distilled 

 water ; the second, the same amount of Detmer's solution with the addition 

 of the decomposed phosphotungstic acid fraction of bacterised peat, extracted 

 as described in the previous communication, in the proportion of 17 parts of 

 dry substance per million of solution ; and the third, Detmer's solution plus 

 the silver-baryta fraction of bacterised peat, in the proportion of 0'35 part 

 per million. 



Thirty healthy plants of Lemna minor of uniform size were counted out 

 into each of the three dishes. The dishes were then covered with glass 

 plates to exclude dust, and were kept in a cool greenhouse. At the end of 

 a week the number of plants in each dish was again counted, their area 

 measured by means of squared paper, and the liquids replaced by fresh 

 solutions. This treatment was repeated weekly, with slight irregularities, 

 until October 20. 



At the end of six weeks the plants receiving the phosphotungstic fraction 

 had filled their dish, therefore the contents of the three dishes were divided 

 exactly into half at the weekly counting, and one-half of each set was 

 discarded. This had to be repeated frequently owing to the very rapid 

 multiplication of the auximone plants, until on October 20, when the 

 experiment was concluded, the number of plants in the respective dishes 

 had then to be multiplied by 256, to obtain the total numbers which would 

 have been derived from the original 30. 



The final figures obtained showed a percentage increase in number over the 

 Detmer's solution of 197 for the phosphotungstic fraction, and 109 for the 

 silver fraction. 



The plants receiving auximones retained their vigour and maintained 



