Note 1 — Chapter I · INTRODUCTION

This idea of a selectivity of the roots has been recently revived by Colin and Lavison (1910) who found that when peas were grown in the presence of barium, strontium or calcium salts no trace of barium could be found in the stem, strontium only occurred in small quantities, while calcium was present in abundance. They concluded that apparently salts of the two latter alkaline metals could be absorbed by the roots and transferred to the stem and other organs, but that this is not the case with salts of barium. They obtained similar results with other plants, beans, lentils, lupins, maize, wheat, hyacinth. Their proof is not rigid, and exception could be taken to it on chemical grounds.