1938] 
“Shuttling” in Argiope aurantia 
69 
the frequent practise of these creatures to put a screen of 
irregular threads on the side of the orb where they normally 
rest. 
If the shuttling were due essentially to asymmetry of fork 
stimulation, it should be relatively inhibited in the case df 
stimulation given as symmetrically as possible. In the 
7-18-36 observations, each of the young aurantias available 
had its first fork-to-dorsum stimulus downward from 
above. Responses to this and subsequent stimulations were 
essentially as follows : 
Spider No. Stimulus No., Direction 
and response Subsequent 
1 
2 
3 
A reach 
L reach 
spread 
A reach, 
spread 
L reach, spread 
A spread 
A spread, 
shuttle 
L shuttle 
back 
L shuttle and back, then 
imperceptible; after 1' one 
shuttle and back, then re- 
fractory to both forks. 
A seize 
L seize 
L spread 
To 6 subsequent L stimuli: 
4 reaches, 2 seizes, no 
shuttle. 
A seize 
L shuttle 
L shuttle 
back 
L, to 7 stimuli shuttle and 
back, then spread, then 
imperceptible. Same pat- 
tern on two subsequent 
series this date. 
A seize 
A reach 
A imper- 
ceptible 
To 15 subsequent L stim- 
uli, all spread or reach 
except 1 shuttle, 1 seize. 
In these and an added number of other observations prior 
to August 1, the indication is, that shuttling is somewhat 
less likely to occur if the stimulus is symmetrical or nearly 
so. In only one of the 7-18-36 trials of stimulus from above 
did shuttling occur, and the failure of shuttling in the case 
of lateral stimulus appears in general a phase of negative 
adaptation. The uniformity of shuttling in a direction op- 
posite to the fork’s approach, is confirmed. The seizings are 
puzzling. It is hard to exaggerate the violence with which 
the diminutive creature would literally hurl itself upon the 
fork, wholly abandoning the nest, and needing to be scraped 
off the fork for return to the nest. Nothing resembling it 
