454 Trans. Acad. Sci. of St. Louis 
balls. All this she did with an air of peace and satis- 
faction in work well done. 
If some wasps can by some sense detect the spiders 
which have been caught and paralyzed by another of 
their kind, and express such resentment toward their 
presence, how much more strange it is that this one 
seemed not to be aware that part of her prey had been 
handled by another wasp, besides myself, or if she did 
know it, cared not a whit. , 
Exp. V. Next I tried a new form of interference, 
placing three spiders in a Sceliphron cell which was only 
in course of construction, being but one-fourth com- 
pleted. So it was not at all surprising that the wasp, 
after a little commotion, promptly emptied this and pro- 
ceeded with her masonry. 
Exp. VI. A wasp had completed her cell and placed 
her first spider there. I removed it, filled the entire 
cell with spiders from other nests and replaced her 
own spider in the front of the cell so she would see 
only her own prey when she returned. However, in 
handling the contents, I broke out a small piece of the 
wall at the opening. When I returned in a half-hour, 
I found that the cell had been emptied and deserted by 
the mother. Why did she go to the trouble of empty- 
ing it if she meant only to desert it? 
Kixp. VIL ‘A new Sceliphron nest appeared complete, 
but was still empty. The insect brought a load of mud, 
but used it to reinforce the nest, then went all the way 
into the empty cell and remained there for four min- 
utes, only her tarsi protruding. What may have been 
her business during that performance, I could not de- 
termine. When she was gone, thirteen spiders (one 
with a small egg attached) from another nest were 
placed in the cell. Upon the second and third trips also 
