Growth o/'Lemna minor in Mineral Culture Solutions. 499 



cellular tissue was much less than in the control plants. The difference was 

 also very evident in the individual cells. In the auximone plants they were 



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A. Series VI 



B. „ VII 



C. " „ VIII 



23456^89 

 Time in weeks 



Fig. 5. 



IO II 12 13 



Detnier's solution in conductivity 'water. 



„ ,, + water extract free from humic acid". 



,, ,, + complete water extract. 



larger and more densely filled with protoplasm, containing larger nuclei and 

 more numerous and larger chloroplastids than in the control plants. This 

 difference was especially noticeable at the apex of young, newly-formed 

 plants. 



These various points are evident from the diagrams on Plate 22, drawn with 

 the camera lucida, of representative plants grown in Series VI and VIII in 

 conductivity water, the two of each set being of the same magnification. 



Interchange of Culture Solutions. 

 When it became evident from the previous experiments that a period of 

 three weeks generally elapsed before the effect of added auximones became 

 very marked in plants which had been taken from their normal habitat, a 

 further experiment was commenced at King's College to ascertain how soon 

 plants grown in water culture with and without auximones would respond to 

 a reversal of these conditions. 



2 u 2 



