. 
86 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
made with a rapidity which often prevents the eye from following the 
motions of the foot and spinnerets. 
When the innermost spiral is reached the aranead swings or strides to 
the hub, takes up her position head downward and bites out the flossy 
guidon, which she takes within her mouth.’ Whether or not it is finally 
rejected I cannot say, but it is certainly retained for some time, and I 
believe is dissolved within her mouth, and swallowed. 
What becomes of the unbeaded scaffold lines which the spider uses for 
weaving in her system of beaded spirals? They are not seen among the 
: concentrics when the orb is finished, and the secret of their dis- 
Spinel appearance is only to be unfolded by watching the architect as 
Scaffold ; - 
Romoved. she proceeds with -her work. It will thus be found that as she 
spins her way from the outer margin toward the centre she 
bites off her scaffolding and permits it to drop away, rolling it up usually 
within her jaws. It has served her purpose by giving her footing while 
engaged in forming the essential part of her structure, and when she 
needs it no longer she removes it, precisely as the mason when “ point- 
ing” his stonework takes dowh his wooden scaffold as he works from the 
top toward the bottom of his wall. I have observed this process repeat- 
edly, as others have done. Mr. Emerton® speaks of “a few turns in the 
centre” apparently confounding what I have called the “notched zone” 
with the special scaffolding, as his figure also shows. ‘The latter is 
not simply a continuation of the former, but is rather an independent and 
permanent part of the orb, having a wholly different use and is separate- 
ly spun. Blackwall says that the “innermost circle” of the spiral scaffold 
is permitted to remain; but my observations, on the contrary, are that all 
the concentrics are removed and the beaded spirals carried to the very 
margin of the free zone. Possibly the habit is not invariable in its 
details; and on the whole presents a good example of intelligent exercise 
of the spinning function. 
Il. 
The efficiency of an orbweb for the capture of prey depends chiefly 
upon its viscidity and strength. The former quality pertains to the spiral 
lines which differ from the other parts of the web in being 
covered at close intervals with minute viscid beads. To these 
the value of the snare as an instrument is chiefly due, for they 
adhere to and melt upon the wings, limbs, and hairs on the bodies of 
insects that strike the web, and thus fatally entangle them. Rennie has 
Spiral 
Beads. 
1 Kirby and Spence, Introduction to Entomology, page 413, are quite correct in their allusion 
to this fact, but the biting away of the cotton like tuft is not necessarily accompanied by 
the opening up of the hub. Blackwall suggested the probably true reason why the central 
space is without viscid beads. 
2 Blackwall, op. cit., page 183. 
8 Hmerton, American Naturalist, ii, 478; Packard’s Guide, page 646; Structure and Habits 
of Spiders, page 64. “ 
