June, 1940] AGRICULTURAL RESEARCH IN N. H. 35 



iier." Another petroleum derivative (a standard, purified household 

 spray kerosene) gave much lower penetration, approximately only 

 one-sixth as much as the lower boiling fraction. 



Among the alcohols maximum penetration was exhibited by 

 methyl. Normal propyl, iso propyl, and butyl, showed closely par- 

 allel rates of penetration, all three being much inferior to methyl, 

 A\hich gave four times as great a penetration rate. Ethyl and oc- 

 tyl alcohols gave somewhat higher amount of penetration than the 

 three just named, but much less than methyl. 



Pine oil gave somewhat lower penetration than the alcohols. 



Considerable work was done with acetone, mesityl oxide and 

 Inityl ether, but each of these requires much additional investigation 

 before results can be considered reliable. Acetone could not be con- 

 fined with any of the cements so far available. Mesityl oxide and 

 Ijutyl ether could be held for a fair observation period, Init show- 

 ed leakage at the end of the complete period of study. 



The AA'ork already done with the petroleum derivatives \\as repeat- 

 ed, in order to verify data already secured. Results of the second 

 investigation agreed substantially with previous results. 



The technique employed in these studies was subjected to a rather 

 elaborate investigation to afiirm its validity. The results of this 

 were satisfactory. Also, extensive wc^rk was d(^ne in calibration of 

 apparatus. 



Results of that part of the investigation which are reasonably com- 

 l^lete have l)een prepared for publication as a research bulletin in the 

 contact insecticide series. The work is conducted bv W. C. O'Kane, 

 J. G. Conklin. L. C. Glover and R. L. Bickle. (PurncU Fvnd) 



The Penetration of Ovicides 



This investigation was planned by W. C. O'Kane, R. L. Blickle and 

 L. C. Glover to shed light on the amount and rate of penetration of 

 various liquids into an insect egg. The liquids studied include min- 

 eral oils of several viscosities and several degrees of saturation, a 

 number of glycerides, and some turpenes. The liquid under study is 

 saturated w ith a dye. the insect eggs are placed in it for a constant 

 period, and the egg is then sectioned, using a freezing microtome. 

 The investigation has afforded the following information: 



Mineral oils of low viscosity penetrated the egg more quickly 

 than oils of higher viscosity. 



iNIineral oils low in unsaturates penetrated more quickly than the 

 ct)rresponding oils containing a larger percentage of unsaturates. 



Mineral oils gave more rapid penetration than glycerides of ap- 

 proximately the same viscosity. 



Steam-distilled pine oil penetrated more rapidly than glycerides, 

 and more rapidly than mineral oils, except those of very low vis- 

 cosity. 



Among the insect eggs used those of the American roach showed 

 most rapid penetration, followed by the eggs of the Colorado potato 

 beetle, and then by those of the Mexican bean beetle. 



Preliminary studies on the relationship of the age of an insect egg 

 to speed of penetration (using eggs of the Mexican bean beetle) in- 



