496 Philippine Journal of Science 1920 
of letters—denoting uncertainty in the data—are treated as 
belonging to the medium group. 
It seems undesirable, considering the discrepancies as to de- 
tails, to attempt to combine these four diagrams into a single 
one, but the following remarks will draw attention to the main 
points on which such a combination might be based. We may 
begin by considering the two total concentrations separately, as 
to the degree of agreement between the data for tops and those 
for roots. For the lower of the two medium concentrations 
KH, PO, 
LM 
High yield 
Low yield 
LM 
Mi LM 
(NH,),S0, .« en 
Fic. 4. Top-yield values for the thirty-five different sets of salt proportions, with low-™ 
total concentration. 
