38 



atode work for over three years and the space devoted to the purpose 

 was large enough to pursue our experiments to advantage. In gen- 

 eral, however, the solutions were tried in the laboratory first to see 

 what effect they would have upon the adult worm. For this purpose 

 numerous cultures of nematodes were kept on hand. In order to 

 test the various solutions upon them we emploj'ed hollow glass slides 

 placing the worm directly in the solution, and where volatile solutions 

 were used we utilized what is known as the Van Tieghem drop culture 

 chamber which consists of a glass cylinder about | in, in diameter, 

 having a capacity of about 3CC., fastened to an ordinary' slide. This 

 gave us a tight moist chamber in which the nematodes were 

 suspended in a drop of water on the under side of the cover slip, the 

 volatile solution being placed in the bottom of the chamber. The 

 number of nematodes selected for treatment varied anywhere from 

 5 to 100. The experiments were confined entirely to the adult worm* 

 and not to the eggs of the nematode which were, however, sometimes 

 present. In some instances the solutions were made up from pure 

 chemicals, in other instances commercial chemicals were used. The 

 following table shows the various experiments made in the laboratory 

 with chemical solutions of different strength. 



*Note. In these experiments various free living species of nematodes were used. 



