New YorK AGRICULTURAL EXPERIMENT STATION. 487 
important and indispensable part in bringing inorganic ma- 
terials into solution for plant food. 
While no data can be given from this experiment to show 
that the soil of the tilled plat is better aerated than that of 
the sodded plat, or for that matter that aeration is necessary 
to the apple, yet the above considerations, necessarily very 
brief, are convincing as regards both points. We are justified, 
without the presentation of specific data, in saying that the 
better growth and greater productiveness of the tilled trees are 
in some degree, and probably no small one, due to the better . 
aeration of the tilled soil. 
The beneficial micro-flora is larger and more active in a tilled 
soil—No experimental evidence is offered to show that the 
flora of micro-organisms is larger in the tilled plat of this 
experiment than in the sodded plat. Such evidence is not 
necessary, for experimenters in this field are well agreed that 
beneficial micro-organisms are found in greater numbers and 
are better distributed in a cultivated soil than in compact and 
uncultivated soils. These lower forms of life, as with higher 
forms, are profoundly affected, both as to their individual well 
being and as to their multiplication, by such environmental 
conditions as food, air, moisture and temperature, all of which 
factors are better regulated for all growth by cultivation. 
One of the objects of tillage, as set forth in the latest agricul- 
tural text-books, is to convert the soil into a suitable living 
place for micro-organisms through the increase of humus, good 
drainage, good ventilation, and a higher temperature. It is 
not unreasonable, therefore, to assume, though specific data 
are wanting, that the greater number and better condition of 
the micro-organisms in the tilled plat of this experiment con- 
tributed to the greater well being of the trees thereon. 
The toxin theory.—There is much evidence to show that all 
plants, to a. greater or less degree, so change the soil in which 
they grow as to make it wholly or practically unfit for a suc- 
ceeding crop of the same kind, There is evidence to show, 
