THE SPIDER AND ITS WEBS. 215 
no other protection than what may be afforded them through com- 
passion, or in consideration of a well-understood interest in the posi- 
tive services which they render. 
Those which suspend their nests to the branches of trees, like those 
which suspend them to our windows, display an evident design to 
place themselves in the wind, where a current of air may waft the in- 
sects to them, or in the path of a ray of light in which the gnat may 
float and whirl. The web does not fall vertically, for such a position 
would restrict it to one current; the spider, like an able seaman, gives it 
a great obliquity, and thus secures a couple of currents, or even more. 
From the extremity of its belly, four screw-plates or tubercles, 
which can be drawn in or out (like telescopes), eject by their move- 
ment a very little cloud, that increases in size from minute to minute. 
This cloud is composed of threads of an infinite tenuity ; each tubercle 
secretes a thousand, and the four, by combining together their four 
thousand threads, make the unique and tolerably strong thread of 
which the web is woven. 
Mark well, that the threads of the intelligent manufacturer are not 
all alike, but of different strength and quality according to their des- 
tination. Some are dry for warping, others viscous for gluing. The 
tissues of the nest intended for the reception of the new-born are of a 
cottony material, while those which will enwrap the cocoon containing 
the eggs possess all the resistant power necessary for the safety of the 
latter. 
When the spider has produced a sufficient quantity of thread to 
undertake a web, it voluntarily glides from an elevated point, and un- 
winds its skein. There it remains suspended, and afterwards reascend- 
ing to its starting-point by the assistance of its tiny cordage, moves 
towards another point; and continues to trace in this manner a series ‘of 
radii all diverging from the same centre. 
The skein stretched, it is busied next in weaving the woof by cross- 
ing the thread. Running from radius to radius, it touches each with 
its tubercles, which fasten to it the circular border. The whole is not 
a compact tissue, but a veritable network, so geometrically proportioned 
that all the meshes of the circle are invariably of the same size. 
