2l8 C. H. TURNER. 



the lower third of the walls of the room. Excepting the space 

 occupied by windows, doors and dado, the walls were plastered 

 in the rough. In the west wall there were two windows (Fig. i, i 

 and 2) ; in the north, four (Fig. i , 3 to 6). The windows of the 

 north wall were close together, being separated by wooden par- 

 titions only one foot wide (Fig. \, B, C, D). Across the top of 

 each window there was a piece of three inch moulding. On the 

 north wall this moulding extended continuously across the four 

 windows. There were two green blinds to each window, one to 

 each sash. These blinds were not quite opaque. The ceiling 

 was painted green ; the walls, including dado, doors and window- 

 facings, cream color. 



In order to have only one entrance for the wasps, the lower 

 sash of window number one was raised half way. All other 

 windows were' closed. This condition was maintained through- 

 out the entire series of experiments. To furnish definite light 

 relations for the beginning of the experiment, the lower shade of 

 window number one was raised about half way and the top 

 shades of windows one and three raised as far as possible. All 

 the other shades were down. After these conditions had been 

 maintained for nearly two weeks a mud-dauber began the con- 

 struction of a nest on the moulding above window number three 

 at a point about six inches from upright B (Fig. i, a). 



When first discovered the wasp had completed nearly half of 

 one cell ; hence it had already made several trips back and forth 

 through window number one. I watched the wasp make several 

 trips, and each time it behaved as follows. On entering the 

 room it would fly obliquely upwards to the upper third of upright 

 B. Then it would fly vertically upwards almost to the ceiling, 

 thence it would fly leftward to the nest. The line of flight from 

 the entrance to upright B was perceptibly curved, the convexity 

 being towards the east. The flight from the entrance through 

 window number one to the nest consumed about half a minute. 

 In departing, the wasp flew downwards in a curve from the nest 

 to the upper portion of the opening through which it had entered 

 the room. After watching the w^asp make several trips in 

 practically the same manner, the following experiments were 

 performed : 



