1162 
The next part of the experiment was a 
series of very careful measurements to 
determine the freedom of absorption of 
oxygen, which is essential to the life of 
the insect while under the influence of 
the insecticide. This part of the experi- 
ment led to the conclusion that it is the 
prevention of the proper absorption of 
oxygen into the body tissues of the insect 
that renders the kerosene, gasoline, car- 
bon disulphide and similar insecticide so 
poisonous. 
“Lime-sulphur is a special rather than 
a general contact insecticide.” Its strong 
persistent ability to take up _ large 
amounts of oxygen and “its ability to 
soften the wax about the margin of the 
scale insect like the San Jose scale are 
the important properties that make it 
efficient as a scalecide.” 
Reference 
Michigan Agricultural College Experi- 
ment Station, Bulletin 11; Geo. D. 
Shafer. 
INSECTICIDES. See Sprays. 
Iowa 
Iowa is 310 miles east and west and 
210 miles north and south. It is part of 
the great Mississippi basin and is mostly 
an undulating prairie, rising in swells 
or small ridges like the waves of the sea 
in the ordinary calm. Beginning with 
the Mississippi river these elevations rise 
gradually higher and higher to a divide 
running diagonally from a height of 1,694 
feet in the northwest to a slight elevation 
in the southeast. There are now no 
swamps, although in early times the state 
was largely covered with swamps. There 
are few natural forests, although in the 
northwest there is a considerable area 
that was at one time covered with trees. 
There are skirts of timber along the 
streams. Two-thirds of the state is 
drained by streams leading to the Missis- 
sippi river. The western drainage is to- 
ward the Missouri river. The northern 
part has a number of small lakes similar 
to those of Minnesota, formed by the same 
action or system of glacial deposits, some 
of them surrounded by a natural wall of 
loose stones, the water pure and clear. 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
The climate is a little severe, the mer- 
cury occasionally dropping to 40 degrees 
below zero. The average rainfall is about 
31 inches. No less than five separate 
sheets of drift cover the state, giving a 
variety of productive soils. 
Iowa is not so well adapted to fruit- 
growing as are some of the states further 
south. Some of the very hardy varieties 
may be grown successfully, but it lies in 
a latitude where the mercury occasionally 
drops to 40 degrees below zero, while the 
climate is not modified by ocean or lake 
breezes, and there are no sections shel- 
tered by high elevations or mountain 
ranges. However, hardy varieties of ap- 
ples, sour cherries, currants, gooseberries, 
strawberries, raspberries and blackber- 
ries are successfully grown for home use 
in all parts of the state. Commercial 
orcharding is not extensively conducted. 
The drainage systems for Iowa are the 
Mississippi and Missouri rivers with their 
tributaries. The principal fruit-growing 
sections are counties bordering on the 
Missouri river and on the Des Moines, 
which drains into the Mississippi. 
The principal apple producing counties 
near the Missouri river are: Fremont, 
159,959 bearing trees; Harrison, 130,898; 
Mills, 242,466; Page, 145,895; Potawata- 
mie, 259,113; Taylor, 112,585. The coun- 
ties on the Des Moines river producing 
the largest number of trees are: Mahas- 
ka, 110,208; Polk, 145,895; Warren, 114,- 
158. 
The total number of bearing apple 
trees in the state is estimated at 5,847,- 
034; the total number of peaches and 
nectarines, 1,090,749; plums and prunes, 
1,155,041; cherries, 908,764; grapes, 
1,983,465; strawberries, 2,917 acres; rasp- 
berries and loganberries, 1,573 acres; 
blackberries and dewberries, 2,279 acres; 
nuts, 163,337 trees. 
GRANVILLE Low TIrER 
Apples Recommended for Commercial 
Planting in Northern Iowa 
Oldenburg (Duchess), Patten (Patten 
Greening), Wealthy, Northwestern 
(Greening), Salome (Trial), Colorado Or- 
ange (Trial). 
