Field Studies of the Non-Social Wasps 465 
pulse that she threw away her mud and cleaned out the 
spiders that I had tampered with, and, more than that, 
when I again bothered her cell by placing spiders from 
other nests in it, she carried them all out and then sat 
on the nest for thirty minutes in a watchful mein, and 
finally brought in mud and covered the inside of the cell 
with several layers, just as though the trouble lay in 
its inadequacy. 
In Exp. XIII, when the mother with an almost com- 
pleted cell brought in a load of mud for the final ring, 
found her cell filled with spiders that I had placed there, 
she withdrew her head with a start as though greatly 
shocked and then went away in bewilderment; she spent 
a long time seeking for her nest, often passing her own 
by as if it belonged to another. Her entire behavior in- 
dicated that she did not recognize the nest as her own. 
In Exp. XIV, a cell was quickly built and as it neared 
completion I filled it with fourteen spiders from an- 
other nest. When the wasp returned with her mud and 
saw the spiders, she calmly sealed the cell and then 
brought more mud to reinforce the plug. This she com- 
pleted with evident satisfaction, in spite of the fact that 
the two most vital steps in the work had been omitted. 
Here we see that ‘‘chain instincts,’’ if they exist, some- 
times miss a cog; in fact, two—egg-laying and provi- 
sioning—have been unconsciously missed here. It seems 
that in this ease the combined impulses created by the 
sight of the cell full of spiders and the presence of mud 
in the jaws were more powerful than the urge to ovi- 
position and provisioning. But even this same mother 
did not respond in the same way when she was confront- 
ed with the same situation the next time; when her next 
cell was finished and IJ stealthily filled it also, and she 
returned with her final mud ball, she was so incensed 
