IQI2] 



SCH REINER &• SKINNER— FERTILIZER SALTS 



35 



of the cumarin is shown in the green weight of the plants taken at 



the termination of the experiment. In table I is given the green 



weight of the series of cultures containing the same amount of 



phosphate ; that is, the series along any one of the horizontal lines 

 in fig. i. 



TABLE I 



Showing the influence of phosphate in overcoming the harmful effect of 



CUMARIN 



Percentage of 



P'Oj IN FERTILI- 

 ZER MIXTURES 



Parts per mil 



lion OF PaOs 



IN ORIGINAL 

 SOLUTIONS 



O 

 10 



20 



30 

 40 



So 

 60 



70 



80 



90 



100 



Number of 

 cultures 

 included 



Green weight of cultures 



Without 

 cumarin 



With 

 cumarin 



Relative (with 

 out cumarin 

 = 100) 



O 



8 

 16 



24 



32 

 40 



48 



56 

 64 



72 

 80 



11 

 10 



9 



8 



7 

 6 



5 

 4 



3 

 2 



21-773 

 22.408 



20.339 



17- 143 

 15.008 



11. 188 



9"3 

 6.915 



4-I7I 

 2.388 



0.932 



I5-370 

 18.835 

 17.140 



I5-350 

 14.085 



11. 150 

 9.005 



6.485 

 4-330 

 2-530 



0-955 



7o 



84 



84 

 90 



94 

 100 



99 



94 



104 



106 

 102 



The last column of the table gives the relative growth between 

 the two sets of cultures, with and without cumarin. It will be 

 seen from the last column of the table that in those cultures in 

 "which no phosphate was present the depression in growth caused 

 by cumarin was greatest, being reduced to 70 per cent of the normal, 

 and that the introduction of 8 ppm. of phosphate caused the growth 

 to rise to 84 per cent of the normal. On further increasing the 

 phosphate content to 16, 24, 32, and 40 ppm., the green weight 

 rose to 84, 90, 94, and 100 per cent of the normal, respectively. 

 From this point on the growth is practically as good in the cumarin 

 set as in the normal control set, thus showing that, on the whole, 

 the fertilizer combinations high in phosphate were practically able 

 to overcome the harmful influence of the toxic cumarin. 



The lessened toxicity of cumarin in solutions high in phosphate 

 is also shown when the results of the experiment are grouped in 

 such a way as to obtain all cultures containing 50 per cent and over 

 of any one of the three constituents, P 2 s , NH 3 , and K 2 0, as was 



