BOTANY. 1009 



with the same plants ^rown in a normal nutritive solution. All the 

 salts in weaker solutions pi'oduced a stimulating- effect on the growth 

 of both wheat and alfalfa. The decrease from the effect was quite 

 regular with the increase in osmotic pressure with all the salts except 

 potassium chlorid, which retarded growth much less than the other 

 salts. With osmotic pressure represented by 3.8 atmospheres, potas- 

 sium chlorid forced alfalfa into bloom earlier than the other pots, and 

 its fertilizing effect was very marked except where the strongest solu- 

 tion was used with alfalfa. With this solution the retarding effect 

 was as great or greater than that of any of the salts of the saaie 

 concentration. 



In order to determine how far the salts were absorbed by the plants, 

 they were analyzed for chlorids and sulphates, and it was found that 

 in case of both potassium and sodium sulphates the more concentrated 

 the solution the greater the amount of salt so taken up by the plant; 

 but in the case of the chlorids the normal amount found in the plant 

 was not increased, but in some cases was actually diminished, by 

 increase in the concentration of the solution. 



The evaporation of water from the salt solutions and the plants 

 growing in them was measured and the results are given in a table, 

 which shows the amount of Avater added to each pot to take the place 

 of that lost by evaporation and to bring it back to the initial weight. 

 The increase in evaporation during June was due to the increased 

 amount of water drawn off* by the plants as they rapidly increased in 

 size. Wheat produced more weight of plant in the nutritive solution 

 alone than in any of the salt solutions, and in every case less water 

 was lost by evaporation and transpiration from the salt solutions. On 

 the other hand, alfalfa produced more weight of plant in the w^eaker 

 salt solutions and more water was lost in these solutions than from the 

 nutritive solution alone. In general, there was greater evaporation 

 from the check pots than from those containing salts. 



The germination and groTvth of peas in solutions of fatty acid 

 salts to the exclusion of mineral salts, O. Lovisox {But. Cen.tbL, 

 83 {1900), Ms. i, pp. 1-12; 2, pp. 33-1^3; 3, pp. 66-75; ^, pp. 97-106; 

 5, pp. 129-138; 6, pp. 185-195; 7-8, pp. 209-221^, figs. ^).— Normal 

 solutions of formic, acetic, and propionic acid were found to penetrate 

 the cells of the seed without causing their immediate destruction. The 

 germination of peas was retarded when subjected to solutions of 77.5 

 per cent normal formic acid, 'o'o.'o normal acetic acid, or 10 per cent 

 normal propionic acid, the effect of the different solutions being in 

 proportion to the molecular weight of the acids. The solutions were 

 found to retard the growth of plants in about the same way that their 

 germination was affected. The average time that plants survived after 



22065— No. 11 2 



