13 



The pots were kept in an insectary greenhouse, and all those of 

 each series were planted on the same day — the first series on the 29th 

 of August, 1907, and the second on the 5th of September, and the 

 third on the 8th of that month. All measurements of mixtures were 

 made with a pipette graduated to hundredths of a cubic centimeter, 

 with the exception of eight of the 4-pot sets, in which the measure- 

 ments were made by drops ; but as these were subsequently duplicated 

 by centimeter measurements, which gave virtually the same results, 

 they need not be separately described. 



In the first planting — that of August 29 — 750 kernels were planted 

 without treatment in fifteen pots, as checks upon the various phases 

 of the experiment; 800 kernels were treated before planting with 

 ordinary lemon oil and alcohol, 1,000 kernels with terpeneless lemon 

 oil arid alcohol, 400 kernels with terpenes unmixed, and 600 kernels 

 with terpenes and alcohol. Where alcohol was used, it was mixed with 

 the oils in one of two proportions, corresponding to the directions given 

 in two difl:'erent circulars issued from my office. In one of these 

 proportions the oil was in the ratio of .3 of an ounce, and the alcohol 

 2.7 ounces, to the gallon of corn, while in the other the corresponding 

 figures were .3225 ounces for the oils and 2.2575 ounces for the alcohol. 

 As a tabulation of the data for these two strengths of the mixture 

 shows no essential difference between them, they are thrown together 

 in the following table. The pure terpenes were used in the proportion 

 of a teaspoonful (.125 of an ounce) to the gallon of corn. 



The main outcome of these plantings is shown in the following 

 comparative table. 



Pot Plantings of Corn Treated with Ordinary Lemon Oil, Terpeneless 

 Lemon Oil, and Pure Terpenes, August 29, 1907. 



Treatment 



None (check) 



Ordinary lemon oil with alcohol... 

 Terpeneless lemon oil with alcohol. 



Pure terpenes 



Terpenes with alcohol 



Per cent of plants up 



ct^ 



A second series of experiments, with plantings made September 5, 

 gives virtually identical results with those of the preceding table ex- 



