CAN STRONTIUM AND BARIUM REPLACE CALCIUM. 73 



especially bad in the Sr and Ba plants, no new leaves developing 

 and the cotyledons remaining' very small and afterwards beginning 

 to fall down. The roots were not developed in both plants. 



2) Barley. (Hordeum distichon.) 

 (See PI. VII) 



The treatment was exactly the same with buckwheat. The 

 seeds were sown in purified sea sand contained in four large 

 funnels and kept in a warm house. On the 5th April, the plants 

 were 3-8 cm. high, and the solutions were then given. During 

 the experiment, no obstacles were encountered. Until the 16th, 

 no difference was observed among the plants, but afterwards 

 the Sr and Ba plants began to suffer slowly. This was especial- 

 ly the case with the Ba plants. The tips of the leaves became 

 yellow and afterwards chlorophyll was entirely destroyed, the 

 leaves becoming white, as if the plants had been kept in the dark 

 for several weeks, and no growth was observed. The Sr plants 

 preserved their green colour a little longer, but afterwards they 

 gradually became dirty green and the tips of the leaves turned 

 yellow. The development of the roots was remarkably bad in 

 both plants. The Ca plants grew most energetically, the roots 

 reached their maximum length, and the leaves were a dark 

 green in colour. The Ca + Sr plants also grew very well and at 

 first showed no difference from the Ca plants, but afterwards the 

 growth became rather slow and toward the end of the experi- 

 ment,*the difference between the two was quite distinct, especially 

 as regards the development of the roots. The Ba and Sr plants 

 suffered more and more as days passed on, and as I could not 

 keep them any longer, the experiment was stopped on the 1 rth, 

 and the plants were carefully removed from the sand, washed 

 well, and the following measurements were made : — 



