BY W. J. RAINBOW. 
357 
her fangs therein, maintains her grasp until death ensues; there- 
upon she envelopes the body in her thread and bears it to a quiet 
spot, where she can devour in peace her spoil. This scene could 
hardly be enacted by the largest Nejyhila on the smallest bird 
known. Such, however, is my belief, and I feel certain that any 
who will observe for themselves, and closely watch the subject, 
will ultimately bear out my view of the case. It is, unhappily, 
too often a fact that observers are in many instances prone to 
hasty conclusions, and in recording these, render unsatisfactory., 
or even useless, observations that might otherwise be of immense 
value as data. 
The webs of these spiders are composed of two kinds of silk; 
one yellow, exceedingly viscid, and elastic; the other white, dry, 
and somewhat brittle. The latter is used in the construction of 
the framework, guys, and radii, and the former the concentric 
rings or spirals. The spirals are exceedingly numerous, and as a 
rule somewhat less than one-third of an inch distant from each, 
other. Between every eight or ten of these circles there is a 
white thread, which, how r ever, does not form a complete circle, but 
is looped up and returned in an opposite direction to a corres- 
ponding point on the other side of the web. These white lines 
are put in before the yellow ones are constructed, and doubtless 
serve to strengthen the huge mesh. 
As the result of experiments with the American species, 
JSFephila plumipes, Professor Wilder proved"* that these spiders 
have the power of regulating the thickness of the thread voided, 
and also that they can produce either yellow or white silk at will, 
and he even succeeded in drawing off both by artificial means. The 
Professor wound off silk from the species mentioned for an hour 
and a quarter, at the rate of six feet per minute, making a total 
of 450 feet, or 150 yards. This he afterwards removed from the 
quill for the purpose of ascertaining its weight, and it was found 
to be one-third of a grain. It was ascertained that it was impos- 
sible to reel off more than 300 yards of silk from a spider at one 
* Proc. Bost. Nat. Hist. Vol. x. p. 200. 
