Wheat tender Different Conditions of Growth . 545 
to the laboratory, washed in water with camel’s-hair brushes and sketched. 
This was repeated twice at intervals of about ten days, by which time the 
plants were too large to be handled in this way. The crop of both wheat 
and barley was very poor, as not only were bird attacks very severe, but 
the ground was almost covered with weeds, chiefly Papaver rhoeas, Matri- 
caria modora, and Sonchus arvensis. The barley crop was better than the 
wheat, and when the barley was almost ripe a trench was dug across the 
Wheat. Barley . 
1 Superphosphate only 6 
2 Unmanured 7 
. 3 Superphosphate + NaNO s 8 
4 NaNOg 9 
5 Superphosphate + K 2 S 0 4 10 
plot receiving superphosphate and the unmanured plot (6 and 7 in table). 
An attempt was then made to wash out the roots with the spray from an 
ordinary spraying machine. Very little root system had developed, 
probably owing to the extremely poor condition of the soil. It was 
therefore decided to examine the roots of some of the ordinary farm barley, 
and another trench was dug in one of the fields where there was a good 
crop of unripe barley. The root systems here were rather better than on 
the experimental plot, but it was exceedingly difficult to wash them out 
without breaking the roots, for the soil was very hard ; about 2 in. at the 
surface were moderately friable, but below that came layers of very clayey 
soil which became a sticky mass when water was sprayed on to it. By 
examining the sides of the trench it was found that very few roots penetrated 
below the top 2 in. or 3 in. and none appeared below the 6 in. level. Another 
method for obtaining the roots was then tried. A small cluster of healthy 
plants was chosen and a 12 in. cube of soil dug out, with the selected plants 
in the middle of the cube. The solid block was transferred to a box 
which just held it and brought down to the laboratory, where the rqpts 
were washed out in exactly the same way as those in the pot cultures. 
Plants from ground which had received farm-yard manure and from ground 
manured with superphosphate were treated by this method, and the results 
described below. 
» 
Barley. Growth of Roots in the Field. 
The field barley was first examined twelve days after sowing. At 
this time the shoots were not visible above ground, but each plant showed 
six or seven roots ranging from \ in. to 1 in. in length. Twenty-one days 
later, i. e. thirty-three days after sowing, the number of roots was 
much the same, 6-8, but the length had increased to about 4J in. and 
laterals were developing. The superphosphate plants showed a rather 
