Growth q/"Lemna minor in Mineral Culture Solutions. 501 



This comparison is also well shown by the following photographs of one- 

 typical dish from each series taken during Periods I and II respectively : — 



Period I. 



Series I. Series II. 



+ Auximones. — Aiixhnones. 



Fig. 6. 



A comparison of the rate of growth in the different culture solutions is 

 best obtained as before by putting the average number of plants in Series I 

 at 100 for each week, and estimating the corresponding numbers for Series II. 

 The figures thus obtained are : — 



