370 APTERA. 
dem. This species spins a curious net, 
which may be often observed extended on 
shrubs and palings ; it is composed of 
very strong threads^ disposed in concen- 
tric circles^ one within the other, and 
crossed, at regular intervals, by other 
threads, as radii. You understand the 
meaning of radii ? -.^ 
Lucy, Oh yes ; papa showed me a 
circle, and drawing a straight line from 
the centre to the outer edge, or circum- 
ference, he told me that it was called a 
radius, and that more than one were 
called radii. ii 
Mother, Very well. These radii, and 
the several circles, are glued to each 
other at the points where they intersect, 
or cross, and thus form a firm and tena- 
cious web : but there is a curious circum- 
stance in this creature's habits : the inner 
circles are broken off every morning, and 
replaced by fresh threads. 
Lucy, Why does it take such un- 
necessary trouble, mamma ? 
Mother, The glutinous substance, of 
