EXPERIMENTS ON VEGETATION IN SOLUTIONS. 351 



With the exception of the mixture used in Period V., there 

 was added to the others also O'l gramme of phosphate of iron. 



The duration of these periods was accidental, depending on 

 fluctuating meteorological conditions of the atmosphere, but was 

 so far regulated that a distant period was marked whenever 

 almost exactly 1 litre of water had been exhaled through the 

 leaves of the plants. At this time the remainder of the liquid 

 was drawn off for analysis, and the vessel filled with a fresh solu- 

 tion. 



In the following the results of the analysis are given along 

 with the chief periods and circumstances of the experiments. In 

 the analytical results in column A, is placed the total quantity of 

 each acid, and salt received by the plant fti that particular period ; 

 in column B, the bases and acids found by analysis in the remain- 

 der of the fluid ; in column c, the difference between A and B, 

 indicating the quantity of bases and acids absorbed by the plants. 

 Further, the relations of the bases to each other, and that of mag- 

 nesia to sulphuric acid (calculated from column A), are given ; the 

 quotients also express the proportions in which these matters 

 were given to the plants at the beginning of the period. Imme- 

 diately underneath, indicated by " absorbed," are placed the same 

 proportions, calculated from column c, in order to show in what 

 ratio the plant has selected these matters (when there does exist 

 a determinate power of selection). 



SUMMARY OF THE FOOD GIVEN , TO A PLANT OF MAIZE 

 AND ASSIMILATED BY IT 



I. Period. From May 12 to June 12. At the commencement 

 the plant weighed 8 grammes * ; and had six leaves with a surface 

 of 264 square centimetres; water exhaled during the time = 1 

 litre. This period was divided into three sections, in which at 

 first dilute solutions were used. The mixtures were in, 



Sectiou I. Section II. Section III. 



Solution of KOP0 5 . . 2 cent. cub. 4 cent. cub. 6 cent. cub. 



Normal solution A.. .. 100 " 200 " 300 " 



Distilled water 198 " 96 " " 



Total fluid 300 " 300 " 306 " 



Phosphate of iron O'l gramme. O'l gramme. O'l gramme 



There were added as the solution was absorbed by the plant, 



* The maize seed were made to germinate in the month of April in well 

 washed sand ; the young plants weighed on the 12th May, 8 grammes ; on 

 drying the residue weighed scarcely more than the seeds. 



