156 
Psyche 
[Vol. 87 
The ball lost most of its adhesiveness after a single long extension, 
but shorter extensions appeared to be reversible. In one case a ball 
taken from a spider was touched lightly against a nearby object and 
then pulled away gently. A small mass of “liquid” stayed on the 
object, and was connected to the ball by a thin, dry thread which was 
not sticky when touched. When I moved the ball several mm farther 
away more of the dry line was drawn out, and when I moved it back 
this line drew back into the ball. This was repeated several times with 
identical results. Probably the dry line was one of the folded threads, 
and its immediate withdrawal into the ball when tension was lowered 
was due to its tendency to resume a folded configuration. In other 
cases a greater quantity of material was stuck to an object and when 
the object was moved away the entire ball rather than a single thread 
stretched with it. Hutchinson (1903) saw similar extraction and 
withdrawal of line in M. cornigera (in this case the line was the bolas 
line from which the ball was suspended). 
The extensibility of the ball had an unsuspected consequence 
which was revealed in photographs taken as the spider swung at 
moths. As seen in Fig. 12, the ball stretched into a line during the 
Fig. 15. Micrograph of fibers inside a sticky ball of M. sp. near dizzydeani from 
San Jose Costa Rica, showing regular folding, and ribbon-like shape of the fibers 
(unmodified illumination of ball on a glass slide; 10/jm = 6.6cm, original magnification 
250X). Photograph by R. W. Work. 
