12 



four per cent, and the "picked apples" two per cent. Or, stated 

 in another form, the ratio of benefit shown by the picked fruit 

 was ninety-five per cent, while ninety-two per cent, of the apples 

 liable to fall from codling-moth injuries were preserved to ripen- 

 ing by the Paris green. 



This tree was low and broad and not too leafy, and was thus 

 more thoroughly sprayed from the ground than the other experi- 

 mental trees. There is also a possible lack of proper correspond- 

 ence between the tree and its check to be taken into account in 

 connection with this remarkable and exceptional result. 



SUMMARY OF PARIS GREEN EXPERIMENTS. 



As a summary statement of the final issues of the Paris green 

 experiments for both years, we may refer to Table VIII., where it 

 will be seen, in brief, that in 1885 fighty-six per cent, of the 

 fruit exposed to damage by the codling moth was preserved to 

 ripening by the poisons applied, and that fifty-nine per cent of the 

 picked fruit had been thus preserved: or that, taking picked and 

 fallen fruit together, sixty-nine per cent., which would otherwise 

 have been sacrificed, had been saved by our remedial measure. 



Furthermore, during 1886 seventy-four per cent, was saved from 

 falling, by a single spraying, and about seventy-two per cent, by 

 three sprayings. The difference unfavorable to the last was doubt- 

 less due to accidental differences in trees and treatment. 



The benefit to the picked fruit apparent from a single spraying 

 stands at forty-eight per cent, and that from twice s]3raying at 

 ninety per cent., while that from thrice spraying falls away 

 to seventy-nine per cent. Or, summarizing still more briefly, we 

 may say, in general, that the results of once or twice spraying 

 with Paris green in early spring, before the young apples had 

 drooped upon their stems, resulted in a saving of about seventy- 

 five per cent, of the apples exposed to injury by the codling moth. 



1 wish especially to emphasize the fact that the results now ob- 

 tained are drawn from computations so made that they may be 

 expected to hold good without reference to conditions other than 

 variations in the treatment itself. The apples protected from in- 

 jury by the codling moth are evidently apples effectively poisoned; 

 and our "ratios of benefit" really express the ratios of these poisoned 

 apples to the whole number treated. These ratios clearly will not 

 vary either with the abundance of the apples, with the abundance 

 of the codling moths, or with anything else except the original 

 treatment, and subsequent accidents afi^ecting the lengih of time 

 the poison may adhere to the apple. This view is, in fact, sub- 

 stantiated by the essential agreement between the results of last 

 year and this, under conditions as widely difPerent as it would be 

 possible to find by ten years' waiting. 



The weatlier conditions prevailing shortly after the poison is 

 applied will doubtless have much to do with its efficacy; but pos- 



