552 Brenchley and Jackson . — Root Development of Barley and 
reached 55 0 F. Barley, on the other hand, is typically spring sown and 
needs a higher temperature before the onset of active growth can occur, 
a mean maximum of over 6o° F. being needed in this case. 
grm. 
5 2 66 80 101 115 - 1 43 185 days after sowing 
Api3 Ap2?Mau Jui June 15 July 13 Aug 24 
Fig. 4. Wheat , shoot/root ratio. 
Field Trials. 
Wheat. Growth of Roots in the Field. 
Owing to pressure of laboratory work it was not possible to wash out 
the wheat roots from Rothamsted soil. Ten Eyck, 1 however, found that 
the main roots grew almost vertically downwards, giving off numerous 
branches which made a fine network in the upper part of the soil, while 
the deeper roots also gave off many branches. The upper roots curved 
outwards before striking down into the soil, acting somewhat as brace roots, 
a condition of things that recalls the stiffening of the barley roots near the 
crown when potash manures were used. 
Discussion. 
At the outset of the experiment it was anticipated that some information 
might be gained as to the effect of various manures on the depth of rooting 
of wheat and barley. Shepperd 2 found in his field experiments that the 
1 Ten Eyck : loc. cit. 2 Shepperd : loc. cit. 
