ARSENICAL COMPOUNDS FOR POISONING THE WORMS. 139 
will show. In fact, we do not doubt that arsenical poisons will in time 
be superseded by insecticides that are harmless to man, but as matters 
stand, the cheapest and most satisfactory remedy has been found in the 
Application of certain arsenical poisons. Another disadvantage of 
arsenical poisons should be borne in mind, viz., the susceptibility of the 
cotton plant to their caustic action, the leaves being more or less blis- 
tered or burnt by an overdose, while leaves, blossoms, squares, and 
even young bolls may be killed by an excess; so that they are valuable, 
cwteris paribus, in proportion as they are harmless to the plant. 
We cauuot give in simple numbers the minimum quantity of any of 
these arsenical poisons to be applied with safety to the plant, and at the 
same time with the desired effect on the worms. This is due to the lack 
of unity in the application and consequent unequal amounts of poisoned 
mixtures distributed per acre. If, e. g., by one machine 50 gallons of 
a given mixture are distributed over one acre, while by another only 
10 gallons are needed over the same area, it is evident that the minimum 
Quantities of poison required per gallon cannot be the same in both 
cases. Further, the size of the plants, the width of the rows, the state 
of the weather, the character of the admixtures used, all have an influ- 
ence in determining the minimum quantity. 
The figures given below must therefore be considered as the average, 
derived partly from trustworthy experiments which we have made, 
partly from the rates which are locally adopted and which have proved 
satisfactory by long practice, but which dilfer widely in different parts 
of the country. It is to be hoped that with the general adoption of 
the most improved machines, which distribute the mixtures most eco- 
nomically, a more uniform rate can be established. 
The question has been raised lately whether a certain amount of 
scorching by arsenical poisons is really so injurious to the plant as is 
generally believed, or to put the question in its extreme form, whether 
a strong overdose of poison does more harm than the worms if they are 
allowed to have full sway? If the worms are very numerous they will 
not only defoliate the plants, but also destroy the blossoms, squares, 
and bolls, with the exception of the largest of these last. They eat 
the bark of the more tender twigs, and they very much injure the lint 
of the open bolls by the excrement and the particles of gnawed leaf 
which fall thereon, and not only stain it, but depreciate its value, since 
no ginning can entirely cleanse it. A strong overdose of poison kills 
the leaves and causes the blossoms and squares to drop, but does not 
so seriously aflect the bolls. Fields stripped by the worms the latter 
part of August do not fully recover till about two months afterwards, 
while those which have been seriously injured by poison recover two 
weeks earlier. It will thus be seen that the injury caused by the worm 
is of a more serious nature than that caused by arsenical poisons, pro- 
vided that the worms have been all killed by the poison. A small over- 
dose of poison blisters or scorches the leaves, or, at worst, kills the 
