58 Winifred E. Brenchley. 
Wheat and Brassica alba. 
With this association matters were most evenly balanced, as 
the analyses give very similar results whether the plants were 
grown alone or in conjunction. The heights of the wheat and 
Brassica , the number of wheat ears formed and fully developed 
the average dry weights of the shoots of both plants were all 
practically the same in every case. The only indication of unequal 
competition was shown by the roots. Brassica roots alone were 
only fairly well developed, whereas wheat roots alone were good 
and fibrous. When associated the Brassica roots were medium, 
while the wheat roots were remarkably poor, with a great lack of 
fibre. It is curious that this deficiency in the root development of 
wheat was not reflected in the shoots ; possibly some difference 
might have manifested itself had the plants been allowed to grow on 
and ripen their grain. 
Wheat and Spergula arvensis. 
Spergula, when grown alone, was variable but fairly strong in 
the shoot, though the roots were small; the average height per pot 
ranged from 16—28 cms. When grown with wheat it was very poor 
indeed, average height 7—10 cms., and the roots were not to be seen 
in the soil. The fall in dry weight was very great, being from 100% 
to 10% for equal numbers of clumps. 
The wheat was more influenced by the presence of the spurrey 
than would have been expected from the small amount of growth 
made by the weed. The roots were somewhat variable (mostly 
good, some medium) instead of being universally good and fibrous, 
and, although the average dry weight of the plants was considerably 
heavier, yet the number of ears produced was the same for equal 
numbers of plants, 18 being formed, of which 11 were fully developed. 
It must be remembered that the wheat was somewhat handicapped, 
as soil B contained so much sand that it was of a distinctly light 
texture, which is detrimental to the best development of the wheat 
plant. 
Summing up these results it seems that definite interactions 
take place when wheat, poppy, Alopecurus, Brassica and spurrey 
are grown alone or when one weed is associated with wheat. All 
five made satisfactory growth by themselves. When wheat was 
grown with poppy, Alopecurus or spurrey the weed suffered in 
various ways, particularly in the reduction of dry matter and in the 
