574 Brenchley .— The Influence of Copper Sulphate and 
These plants were measured during growth for about seven weeks, and 
at the close of the experiment those in one series were divided into root and 
shoot, separately dried for two or three days in a steam oven at ioo° C., and 
weighed, in order to find the amount of dry matter present. 
i: 12,500 to 1 : 100,000 C.S. solution checked the root growth entirely, as 
both measurements and weights indicated. The shoots had made a certain 
slight increase in length, but the dry weights were insignificant. 1:250,000 C.S. 
Total. 
Shoot. 
Root. 
Curve 2. Showing the mean values of the dry weights of three series of barley plants grown in 
the presence of copper sulphate with nutrient salts. 
3. 1 : 50,000 C.S. 7. 1 : 1,000,000 C.S. 
4. 1 :100,000 ,, 8. 1 : 2,500,000 ,, 
5. 1:250,000 „ 9. 1:5,000,000 „ 
6. 1 : 500,000 ,, 1. Control—glass distilled water. 
seemed to be a transition point, as below this concentration marked im¬ 
provement resulted, though none of the plants grown with C.S. reached the 
level of those in pure glass distilled water with nutrient salts (PI. XLVII, 
Fig. 2 : Curve 1). 
Further experiments made later in the year afforded similar results. 
In this case the concentration of the toxic salt was further reduced to 
1 : 5,oco,coo,but even at this dilution the C.S. seemed to exercise a deleterious 
action, as the plants did not make as much growth as in its absence. 
(Curve 2.) 
