SOME EFFECTS OF SODIUM ARSENITE 5 
In the recent work of Stewart and Smith (38, 39) with pot cul- 
tures it was shown that arsenic in soil acts as a stimulant for certain 
plants. In the case of beans, potatoes, and peas 25 parts of arsenic 
per million of soil resulted in increased vigor. Wheat was stimulated 
with as high as 75 parts per million of soil and radish even with 250 
parts per million. Most of the stimulated plants showed no increase 
in weight, but radish increased in size and weight. Susceptibility 
to arsenic varied with the different plants. Growth was checked by 
the following quantities (parts per million) : Bean, 50; wheat, 52; 
potato, 78; pea, 193; radish, 940. When plants died from a killing 
concentration of arsenic the following quantities were found in the 
tissue (parts per million): Wheat, 269; potato, 524; bean, 678; 
radish, 940; pea, 1,190. 
Stimulation by arsenic is reported also by Stoklasa (40) in the 
case of sugar beets. The arsenic was supplied through superphos- 
phate in which there usually is 0.01 per cent of arsenic. Sugar cane 
was likewise stimulated. Jar vis (33) reported that copper arsenate 
bait, as used for white grubs, produced a noticeable stimulating effect. 
His controlled experiments in earthenware pots showed that treat- 
ments representing 113 and 226 pounds of Paris green per acre of 
sugar cane produced shoots averaging 10 inches as compared with 
7.5 inches in the untreated pot. From 100 to 200 pounds of As 2 3 
(commercial) produced shoots of 27.8 inches as compared with 26 
inches for the untreated. 
TOXIC EFFECTS ON ANIMALS 
The use of arsenic on the farm is always accompanied by more 
or less danger to the livestock. Farm animals, especially cattle, are 
attracted by the brackish sweet taste of arsenic solutions, according 
to Bevan (6). He reports that in 1908 many cattle were acciden- 
tally poisoned in the attempt to exterminate the locust (insect) with 
sodium arsenite. In dipping cattle, juice of the native aloe plant 
was added to the arsenic and acted as a repellent to keep the cattle 
from drinking the solution or licking each other. Barnum (-5), of 
California, reported that where he used sodium arsenite for control 
of the morning-glory, stock had a preference for the sprayed plants. 
He also warns against the fumes which are generated where arsenic- 
treated weeds are burned. There evidently is a need for further in- 
vestigation of substances which can be used with poisonous weed 
killers and which will act as repellents to- livestock. 
Since arsenic is attractive to animals, they may easily secure a 
fatal dose from treated plants or from poison bait or even from the 
ground where arsenic has been applied. Blyth (7) sets the standard 
medicinal dose of arsenic (As 2 3 ) for adult humans at 2 to 5 milli- 
grams; dangerous dose, 0.13 gram; for a horse the dangerous dose 
is 1.9 grams ; for a cow 0.64 gram, and for a dog 32 to 64 milligrams. 
He says that poisoning of cattle can not occur through eating grass 
that has taken up arsenic from the soil through the roots. To quote 
(p. 535) : 
It has, however, been shown by Gorup-Bezanez that if arsenious acid be mixed 
with earth and plants grown in such earth, they only take up infinitesimal 
quantities of arsenic. Hence, in cases of cattle poisoning, any defense based 
upon the alleged presence of arsenic in the pasture will be more ingenious 
than just. 
