810 
THE PRINCIPLES OF BOTANY. 
From these experiments, then, we may conclude that the 
different types of crop-oats are derived from the Avena fatua 
or wild oat, but besides this they open out a subject for in- 
quiry of great practical interest and importance, which may 
he clearly stated as follows : — 
If by cultivation the wild oat assumes the cultivated form, 
then by degeneracy cultivated oats may become wild ones. 
Those who know what a detestable weed is the wild oat 
wherever it occurs, and how difficult it is to eradicate, will at 
once see the cogency of the question involved. 
Farmers in some districts, and more especially on stiff clay 
soils, have ever objected to the cultivation of oats, as they had 
always maintained that they left behind a crop of weed-oats. 
This, which was never a favorite idea with the botanist, who 
is generally too much inclined to species making, seems now 
to have a basis of truth ; for not only is it confirmed by the 
experiments described, hut observation of an independent 
kind points to the same truth. 
On examining the produce of shed or accidentally-scattered 
oat seeds, the first crop will often present the wild tendency 
in a partial reversion to the hairy state, an elongation and 
thickening of the awn, and a lessening of the .size of the ker- 
nel, and this more particularly on heavy soils. It was indeed 
an observation of this change in oats scattered on forest 
marble clay which induced us to try the experiments above 
detailed ; and as the subsoil of our botanical garden is the 
same clay, we were perhaps indebted to this cause for arriving 
so soon at such signal results. 
Again, it is known in farming that some clay land will 
never produce heavy oats, a sample however good is sure to 
degenerate upon such soils. Hence, then, the foregoing expe- 
riments and observations lead to the following conclusions : — 
1st. The wild oat is perhaps not a native of Britain, hut 
derived through the degeneracy of the cereal crop, and 
hence its occurrence only as an agrarian. 
2nd. The cereal oat on the contrary is the result of the 
impress of cultivative processes upon the wild form, and as 
such is liable to lapse into the wild state with greater or less 
celerity, according to the circumstances of the soil and 
situation. 
These conclusions are of practical value, as they show the 
direction in which experiments should be conducted in order 
to attain to varieties, it being a well-known fact that one 
variety is suitable for one soil and another for a different kind 
of land. And again, as some forms of plants would seem to 
have the tendency of wearing out by long cultivation, so we 
