INSECTICIDES. 409 



phide for five minutes. The carbon bi-sulphide was put 

 into a flask and slightly heated, the vapors passing over a 

 bottle containing the egg-clusters, condensing and wetting 

 them, which caused the eggs to become white and soft, after 

 which they all dried up. Two lots of eggs exposed to the 

 vapors of carbon bi-sulphide, in a similar manner, for ten 

 and fifteen minutes respectively, were completely destroyed. 

 January 19. Five egg-clusters, placed in a tin box covered 

 with paper, were treated for fifteen minutes with carbon bi- 

 sulphide, which caused them to grow white and soft, thus 

 destroying them. January 21. Five egg-clusters were 

 treated with cold vapors of carbon bi-sulphide for fifteen 

 minutes, care being taken that the vapors should not wet 

 the egg-clusters. The eggs apparently were not affected, 

 and, by the 24th of March, about one-half of them had 

 hatched. January 25. Five egg-clusters were treated for 

 fifteen minutes to the action of cold vapors of carbon bi-sul- 

 phide. The eggs were placed in a glass, which was put in 

 a large tin box containing carbon bi-sulphide. The eggs 

 were not affected by this treatment, and, by the 24th of 

 March, all had hatched. February 9. A number of egg- 

 clusters were treated in the same manner as in the preced- 

 ing experiment, and, although the eggs did not appear to 

 be affected, none hatched. 



Calcic Chloride. January 21. One egg-cluster was 

 soaked for half a day in a solution of calcic chloride, made 

 by dissolving one-eighth ounce of calcic chloride in two 

 cubic centimeters of water. The solution did not penetrate 

 the egg-cluster, and nearly all the eggs hatched. 



Corrosive Sublimate. February 1 . A few crystals of 

 corrosive sublimate were dissolved in alcohol, and the solu- 

 tion poured over five egg-clusters. March 22, some of the 

 eggs had partly hatched, but the caterpillars soon died. 

 February 1. Five egg-clusters were treated in the same 

 manner as in the preceding experiment. Two or three 

 caterpillars hatched and others came partly out of the shell, 

 but, March 22, all were dead. Three other lots of eggs were 

 treated in the same manner, March 3. None of these eggs 

 hatched. 



