538 
Bottomley. —The Significance of Cert am 
Table IV. 
Series. Weight of set of 1 8 plants. 
X. Complete food solution Original weight 3*20 grm. 
Weight after 16 days 3*37 grm. 
After further 17 days 3*20 grm. 
After further 17 days 2*85 grm. 
II. Complete food solution plus silver 
fraction ......... Original weight 3*17 grm. 
After 16 days 3*63 grm. 
After further 17 days 4*29 grm. 
After iurther 1 7 days 5*05 grm. 
Percentage gain or 
loss in weight. 
+- 5*3 % 
+ o-o% 
+ 14'5 % 
+ 35*3 % 
+ 59*3 % 
Diagram 2 (below) shows the variation in weight of the seedlings 
throughout the experiment, the dotted curve representing the series 
in pure food, while the unbroken curve shows the effect of the addition 
of the silver fraction. 
Diagram 2. 
In this experiment the plants growing in pure food solution made no 
growth beyond the small amount which could be accounted for by the 
