76 AMERICAN SPIDERS AND THEIR SPINNINGWORK, 
passed down 1 and along D to 3, where attachment was made, and radius 
3 was formed. Once more the centre was sought, and passing along the 
line A the point 4 was reached and another radius there fastened. Thus 
on from 4 to 5, from 5 to 6, and so around the entire circle. The mechan- 
ical advantage of this order is apparent. Several times the central termini 
of the radii were strengthened by lapping threads across them. 
This tendency to alternate apposition I have frequently observed in 
various species, and its character will be better shown by giving several 
other schemes of the order of progression in spinning radii, The 
schemes do not present a complete sequence of the radii from 
the very beginning, but number from the point at which I hap- 
pened to catch the spider at work. They are to be read as in Fig. 72, the 
order of numerals showing the relative position of the radial lines in the 
order of their spinning. The series will show, I think, that while no abso- 
lute mathematical regularity marks the succession, some method of alterna- 
tion evidently dominates the spider’s movements. She knows the necessity 
Order of 
Radii. 
10 
Fic. 73. Theorderofspinning 1G. 74. Order of inserting Fic, 75. Orderof six radii. Fic.76. Orderof 
in twelve radii. Epeira ver- nine radii. five radii. 
tebrata. 
which exists for balancing such a peculiar and delicate structure, and 
adopts her mode of spinning to the exigencies of her spinningwork. 
Blackwall states that after the completion of the radii the spider pro- 
ceeds to the centre, turns around and pulls each radius with her feet to 
ascertain its strength, breaking such as are defective, and replacing them 
by others. I have never seen anything of the kind; the spider in settling 
herself and gathering the radial lines into her eight claws naturally jerks 
them somewhat. But no such purpose was ever suggested to my mind as 
that declared by Blackwall. He also says that the radii are composed of 
double lines, a statement which my observations contradict.t I have. seen 
very many radii spun, but have never observed any one overlaid or doubled 
(if that be the meaning) as is often the case with foundation lines. On 
the contrary they were always composed of one thread drawn out in the 
usual way from the spinning spools. 
Rennie in his remarks upon the construction of an orbweb expresses 
the opinion that the most remarkable circumstance in the process is that 
1 Nets of the Geometric Spiders, page 182. 
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