62 
AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
types (II, IV, and V), high partial concentrations of H2PO4 characterize 
the good solutions for the higher temperature, while lower concentrations 
of H2PO4 mark the good ones for the lower temperature. It is thus sug- 
gested that the H2P04-relation (to growth and to temperature) may be 
the reverse of the K-relation. Potassium phosphate being employed in 
types I and VI as the only source of K as well as of H2PO4, a sort of antagon- 
istic effect might be expected in these cases, and this expectation seems to 
have been realized. A study of the two groups of good solutions for each 
of these two types suggests an inversion of the H2P04-relation {low partial 
concentrations for the higher temperature, etc.) and a masking of the 
K-relation, as has been mentioned. Type III furnishes no evidence in this 
regard. 
It appears from these results that temperature is of prime moment in 
determining the mineral requirements for good germination and initial 
•growth in this wheat, at least within the general limits of these experimental 
tests, and it seems safe to suppose that other climatic conditions may not 
be without influence. It is suggested that some of the unexplained dis- 
crepancies that are commonly encountered in comparative studies on plant 
salt requirements and on the application of fertilizers to agricultural soils, 
may be related to climatic influences. It seems clear that all influential 
conditions should be quantitatively considered in such studies. 
