igoS] 



MAGOIVAJV^TOXIC EFFECT OF COMMON' SALTS 



47 



wheat in the MgCl, solutions made a growth almost equal to tliose 

 in CaCla, but after fifteen days the roots in the MgCl, were dead, 

 while those in the CaClj series were still living, even in such high 



concentrations as 0.12 m. After twenty or twenty- 

 five days the plants in CaCl, solutions were in 

 advance of those in KCl and NaCl. In all the 

 solutions the limit of growth was reached in about 



.18 



.J 



-08 



.06 



,04- 



.02- 







thirty days. 



It is significant to note the effect of these salts 

 on the general appearance of the roots : CaCl^ favored 

 the development of root hairs; a fine growth of these 

 occurred in the 0.06 m solution and throughout all 

 the lower dilutions of the series. Also many side 



branches were produced, making a thrifty- 

 looking root system. 



Not even in the lowest concentrations 

 of KCi and NaQ were tlie root hairs 



developed as well as in 

 CaCU 0.06 w and those in 

 the weaker solutions were 



d 



2 00 mf/z. 



iOQ mm. 



^QQmm. 



a 



Fig. I.— Curves sHowing the growth of roots of wheat in salt solutions; fl, diMffled 

 water; 5, MgCl.; c, NaCI; i, KCI; e, CaCU- The ordinates represent concentra- 

 tions (parts molecular); the abscissae, the aggregate length of roots per plant (m miiU- 

 meters). 



unthrifty 



dun 



white color, and as to branching were next to CaO,, although the 

 branches were thicker and shorter than in CaCl,; the braiKh^ 

 were most abundant at o . 02, o . 04, and o.c6m. In CaCl, branching 

 was practicaUv the same throughout. In NaCI a fe^ stunted branchy 

 developed and after twenty days the roots were of a yeUow color m aH 

 ♦v,„ i.:iu .„^-„„: ^.wr, in n.o2 «. In MgQ, neither 



concentrations 



produced 



