10 
check. This was due to rainy weather, which interrupted the plant- 
ing; but as sixteen days elapsed between the planting and the in- 
spection, there was doubtless ample opportunity for the transfer of 
all living root-lice from the weeds to the corn, — a conclusion to 
which I think no one will take exception who has been accustomed to 
observe the corn-field ant in charge of the corn root-aphis. 
Additional to this, the difference in the treatment of the plats 
was the disking of the experimental plat three times and its harrow- 
ing once, and the differences between these plats with respect to ants 
and root-lice are to be taken as due to this additional and repeated 
stirring of the soil of the experimental plat. '■ 
June lo, two hundred and twenty-five hills, distributed over five 
different rows of the experimental (B) plat, were carefully exam- 
ined by Dr. Folsom by digging up the corn and counting the ants 
and root-lice found upon the roots and in the hills. The rows 
chosen for these counts were taken from various parts of the field, 
being respectively the first, seventh, ninth, twentieth, and thirty- 
second of the entire plat. The last, it will be noticed, was the row 
next adjacent to the check plat. In the latter plat (A) seventy-five 
hills were similarly examined from the first, second, and ninetieth 
rows. 
For convenience in comparison, the numbers given will be those 
for a hundred hills of corn taken as a unit. It thus appears (see 
Table I.) that twenty-eight per cent, of the hills of the check plat 
(A) were infested with ants, and that on the experimental plat 
ten per cent, of the hills were so infested ; that seventeen per cent, 
of the check hills were infested by root-lice, and three per cent, of 
the experimental hills ; that one hundred of the check hills contained 
2263 ants, and one hundred of the experimental hills, 185 ants; that 
one hundred of the check hills contained 858 root-lice, and one hun- 
dred of the experimental hills, 79 root-lice. Or, more briefly stated, 
the untreated or check part of this field contained in equal areas, 
about twelve times as many ants and three times as many hills in- 
fested by them, and about eleven times as many root-lice and six 
times as many hills infested by them, as did the treated or experi- 
mental plat. 
