58 THE PLANT. 



performs a similar part in others ; and if one plant may 

 properly be called a chlorine plant, others may with equal 

 propriety be termed iodine plants, or manganese plants.* 

 (Prince Salm-Horstmar.) 



The diversity in the amomit of iodine in different 

 varieties of fucus (Goedechens), or of alumina in various 

 kinds of Lycopodium (Count Laubach), remains, indeed, 

 unexplained ; but the power of plants to withdraw 

 substances like iodine, even in the smallest quantities, 

 from tlie sea water in which they grow, and to accumu- 

 late and retain them in their organism, can only be ex- 

 plained upon the assumption that these substances have 

 entered into combination mth certain constituent parts of 

 the plants, whereby as long as the plant lives they are 

 prevented from returning to the medium from which they 

 were taken, f 



It might be supposed that plants become satm^ated with 

 the substances absorbed from the air and from the soil ; 

 and that all materials offered by the soil in solution, or 

 made soluble by the cooperation of the roots, are absorbed 



* The examination of the following water-plants revealed the 

 presence of considerable qtiantities of manganese and iron in their ash, 

 though the water in which they grew apparently contained no trace 

 of manganese : — Victoria regia {in the leaf-stalk principally manganese, 

 in the leaf iron); Nymphcea ccendea, dentata, lutea\ Ui/drocharis 

 Humhoklti ; Nelumbiwn asperifoliujn. (Dr. ZuUer.) 



f With respect to the copper in the grains of wheat and rye, which 

 Meier of Copenhagen has sho^vn to be a constant constituent of both 

 seeds, Forchhammer (Poggendorff 's ' Annal.' xc. 92) remarks : — ' It is 

 an old and approved practice to steep grains of wheat, intended for 

 sowing, in a solution of sulphate of copper. The iisual explanation of 

 this practice is, that sulphate of copper destroys the sporules of blight 

 to which the wheat plant is liable, an explanation which it is not my 

 intention to dispute. Still it might also be held, supposing copper to 

 be an essential constituent of wheat, that the practice in question 

 serA'CS to supply the copper necessary for the vigorous growth of the 

 plant.' 



