SUMMARY AND CONCLUSIONS. 53 
have been investigated, three of them several times in consecutive 
years, on one type, and three areas on the other type. The 
history of each area has been given, and also in the case of six of 
the areas the chief details of the seeds-mixtures used in laying 
them down to grass (Table IV., p. 16a), 
Some variation has been found in the behaviour of the same 
species on different areas on the same soil type, and considerable 
differences on the different soil types. 
In drawing conclusions for the two area groups it is necessary 
to bear in mind not only that they are not comparable in soil, but 
that their history is also quite different. Areas 1-4 have been in 
regular cultivation on the long rotation system, so that relatively 
short-lived plants would tend to be perpetuated, while more 
permanent plants, unless capable of surviving cultivation, would 
be eradicated or would have no chance of recolonising the ground 
unless especially adapted. These areas are also in constant 
communication with other parts of the farm, and particularly with 
the farm buildings, as they are largely grazed by cattle, so that 
although perhaps not actually manured they are still affected by 
their position. Even Area 5, which had been under grass for a 
long period prior to the rotatioa during which it was examined, 
would have been affected by its proximity to the farm buildings, 
and all these areas are practically surrounded by land treated in 
the same way. 
Areas 6 and 7, on the other hand, had only been through 
one period of cultivation since they had been for a long period in 
the grass-heath condition. They were also remote from the farm 
buildings, and formed part ofa sheep-walk. There was practically 
no communication between them and the land under regular 
cultivation, and they were almost entirely* surrounded by grass- 
heath or by uncultivated land. In this case, therefore, plants 
which are short-lived under the grass-heath conditions would have 
disappeared, and even when the land was brought under cultiva- 
tion they would not easily be re-introduced, This is probably why 
1 Entirely except for a few yards where Area 7 joins the cultivable part ef 
the field in which Area 4 is situated, 
