94 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 
lated with approximate accuracy. The example chosen was a snare of Epeira 
sclopetaria five inches long by three inches wide, and the calculation showed a 
total of 140,800. This is an orb of only medium size; in many webs the 
number is certainly much larger, in some several times greater, although in 
others it is doubtless greatly less. Blackwall calculated that a net of Epeira 
apoclisa from fourteen to sixteen inches in diameter contained upwards of 
one hundred and twenty thousand viscid globules. ‘“ Yet it will complete 
its snare in about forty minutes if it meet with no interruption.”! 
That the viscidity of the spirals depends upon the beads, and that the 
latter are placed upon the former, is of course proved by the effect of rain, 
which separates the beads from the spiral line. But it may be also 
ae shown by scraping or rubbing off the globules with which the line 
Paci is studded. This leaves an inadhesive line, apparently of the 
same constituency as the radii and other parts of the snare. An 
easy way to demonstrate the fact is to insert a bit of glass beneath the 
viscid portions of a web. The beads will adhere to the glass, if carefully 
handled, so as to show distinctly the spiral strings in their proper relations 
to the radii. By a little gentle manipulation with a camel hair brush or 
other small object, the beads will be separated from their strings and melt 
upon the glass, showing the string in the midst of the glutinous matter as a 
straight silken thread. 
I feel well satisfied that the viscidity of the beads varies on webs of the 
same species at different times, and it is probable that the degree of 
viscidity is determined by the condition of the spider. When it is well 
fed the secretions are abundant, but after long periods of fasting the 
viscous quality of the secretion seems to be weaker, or the secretions being 
less in quantity the amount distributed upon the lines is greatly dimin- 
ished, and hence the effectiveness of the spiral strings is decreased. 
When exposed to the desiccating influence of the sun, and air briskly 
agitated, the nets of geometric spiders lose their adhesive property ; ‘ 
but when formed in situations from which the light is excluded, and 
where the atmosphere is not liable to be perceptibly disturbed, they retain 
their viscidity for a long period. Blackwall says that upon a net of 
Epeira diademata constructed in a glass jar, which was placed in a dark 
closet, where the temperature was not subject to great or sudden fluctuations, 
the globules preserved their adhesive power almost unimpaired, and the 
last formed spiral line its elasticity for more than seyen months.? 
I placed a snare of Argiope argyraspis in my study October 3d, 1882. 
It was spun within a wooden breeding box, the front of which was covered 
by a sliding glass door, the back by wire cloth. It was thus exposed to 
light and air, in a well heated room. Examined as late as April 17th, 
1883 (five and a half months after construction) the beads were found to 
1 Brit. Assen. Reports, 1844, page 77. “Spiders of Great Britain,” page 10, Introduction. 
2 Transactions Linn. Society, 1829, Vol. XVI., page 479. 
tic plete: ele a i 
