46 BOTANICAL GAZETTE [january 



placed in the solutions. As the object of this investigation was to 

 find the growth made by the seeds in the different solutions, this 

 method was not practicable, and the seeds were supported on filter 

 • paper^ so that they might germinate in the solution from the 

 beginning. 



Twenty or more seeds were placed in each solution. In general 

 the germination was quite uniform. Usually seven duplicate series 

 of experiments were made. While some series made a better growth 

 than others, the comparative order of toxicity was not changed. In 

 aU concentrations final examinations were made when the roots had 

 reached the Umit of growth. The solutions were aU titrated against 

 standard silver nitrate solution in the beginning and great care was 

 taken in making up the various concentrations. 



To keep the solutions at the same strength was a problem which 

 received careful consideration. As little salt was taken by the plants 

 the first few days, it was found perfectly safe to replenish the loss 

 due to evaporation by adding distilled water. When the solutions 

 were found by titration to be too weak, however, they were replaced 

 by fresh solutions. 



Several concentrations of chlorids of Ca, K, Xa, and Mg were 

 ^ised, these salts being taken because tliey represent the bases most 



:n the soil. In order that the effects of the cathions might 

 be dearly evident, only one anion, chlorion, was used. Control 

 experiments with tap and distilled water were alwavs carried on 

 with each series, the water having been distilled with especial care 

 to avoid all traces of metals in solution. 



^ The plants made a better growtli in distilled water than in any of 

 the salt solutions, which were thus shown to exert a toxic rather than 

 a stimulating effect at the concentrations used. While a marked 

 difference in the degree of toxicity of Ca, Mg, K, and Na was clearlv 

 iwticeabic m the roots, the tops were more neariv aUke in equi- 

 mokcular solutions of the salts, except in the stronger concentrations 



!!f ^' "" ^^""^ ^"1^ g^o^^-^ of either roots or tops occurred. 



Ihe order of germination was noteworthv. The seeds in KQ 

 and NaCl were the first to send out roots, and for several davs remained 

 m advance of those in CaCl. and MgCl,. For the first five days the 



« The method is described bv C^n^vrrr^rr^ n^^ r- . .^.,__ . . _ 



commoa 



