54 
Winifred E. Brcnchley. 
Dr. Hutchinson indicate the possibility that bacterial activity may 
play a part in determining the injurious effects of the grass roots, 
for apparently, when the experiment was carried out under rigidly 
aseptic conditions, no harmful effects were obtained.” 
Altogether, the whole matter is very undecided, and it is as yet 
impossible to formulate any definite statement on the matter. 
For the past four years pot experiments have been carried out 
at Rothamsted with crops and weeds growing in association, wheat, 
barley and buckwheat being used as crop plants, Alopecurus agrestis, 
Brassica alba, Papaver Rhceas, Spergula arvensis being selected as 
weeds on account of their great prevalence on certain types of soil. 
All the experiments were carried out in the same pots under similar 
open air conditions. 
Experiment 1, 1913. 
Soil was taken from a wide path in Little Hoos field, which had 
not received any special treatment or manuring. The soil was 
sifted to remove large stones, and half of it (A) was mixed with 10% 
of coarse sand to render it more workable, the other half (B) 
receiving 35% of sand to make the texture appreciably lighter. 
Thirty pots were filled with each lot of soil so prepared. Large 
glazed earthenware pots were used, weighing about 70 lbs. when 
filled, and seeds of wheat and various weeds were sown on March 
31st in sets of six pots each. The pots with wheat or weed alone 
received twice as much seed as was sown in the mixed pots ; i.e., 
two parts of wheat or weed when alone, and one part wheat + one 
part weed when mixed. The following combinations were grown :— 
A. soil. Papaver Rhceas + Papaver Rhceas, Papaver Rhceas 
+ Wheat, Wheat + Wheat, Wheat + Alopecurus agrestis, 
Alopecurus agrestis + Alopecurus agrestis. 
B. soil. Brassica alba + Brassica alba, Brassica alba-\- Wheat, 
Wheat + Wheat, Wheat + Spergula arvensis, Spergula 
arvensis + Spergula arvensis. 
The Wheat used was the same as that sown on Broadbalk the 
previous autumn—Squarehead’s master. The Alopecurus 
agrestis was seed procured from Broadbalk in 1912, Brassica alba 
was gathered from a field on Westfield Common, Harpenden, 
Papaver Rhceas was obtained partly from Rothamsted fields and 
partly from Sutton, Spergula arvensis was from Sutton. The 
Papaver Rhceas from Sutton was not altogether true to type— 
one pot sown with it yielded plants of a garden form, and so had 
to be rejected in recording the results. 
