carefully placed on the water surface, the leaf floated; 

 it remained fresh for about a week. Some first instar 

 corn borer larvae transferred to a leaf tended to wander 

 around and to come in contact with the water surround- 

 ing the leaf. In order to prevent the water from being 

 drawn onto the surface of the leaf following contact 

 with the water by the larvae, a thin film of petroleum 

 jelly was applied around the edges of the leaf and 

 around the hole in the center of the leaf. It was found 

 advisable to treat the leaf on the underside as well. In 

 order to prevent flooding of the upper surface of the leaf 

 when it had been treated with wetting agents, the gutter 

 formed by the midrib was closed at both ends with bees- 



wax. If it was necessary to increase the bouyancy of 

 the leaf, a piece of wax paper of somewhat smaller size 

 was floated beneath the leaf. The leaf was placed in a 

 crystallizing dish of such size that there would be clear- 

 ance of at least an inch between the leaf and the wall 

 of the dish. The floating leaf was held in the center of 

 the dish by a simple, triangle-shaped anchor made of a 

 bent glass rod. Around this anchor the leaf could turn 

 freely, provided the hole was made large enough. With 

 the help of this anchor the leaf could be lifted out from 

 the water for examination and replaced at any time. 



It was sometimes necessary to cover the dish in 

 order to reduce the evaporation of water. Class or other 



Fig. 7. — Airangemenl HosigneH to approximate the conditions prevailing in the whorl of a young corn plant. A 20 x 90 mm. 

 double strength extraction thimble. A, is reinforced with a band of lacquer around the lip and two vertical strips of lacquer on 

 opposite sides; also, it is provided with a cork that has been softened and wrapped in tinfoil. A coil of wire, B, about 2-1/4 

 inches long, narrow enough to fit easily in the extraction thimble, and with the lower end somewhat constricted, is used as a 

 holder for a rolled piece of corn leaf, C, and inserted, D, in the extraction thimble. The thimble is suspended by the cork 

 stopper in a 25 X 150 mm. culture tube, K. In the bottom of the tube is an inch of water or saturated salt solution, if either is 

 necessary to maintain the humidity at a specific level. The culture tube is covered, F, with an aluminum cap. 



