228 FOOD OF INSECTS. 
is furnished with a multitude of tubes, so numerous and so exquisitely 
fine, that a space often not much bigger than the pointed end of a pin is 
furnished, according to Reaumur', with a thousand of them. From each 
of these tubes, consisting of two pieces, the last of which terminates in 
a point infinitely fine, proceeds a thread of inconceivable tenuity, which,, 
immediately after issuing from it, unites-with al! the other threads into one, 
Hence from each spinner proceeds a compound thread ; and these four 
(or six) threads, at the distance of about one-tenth of an inch from the 
apex of the spinners, again unite, and form the thread we are accustomed 
to see, which the spider uses in forming its web. The threads, however, 
are not all of the same thickness, for Leeuwenhoek observed that some of 
the tubes were larger than others, and furnished a larger thread. Thus, a 
spider's thread, even spun by the smallest species, and when so fine that it 
is almost imperceptible to our senses, is not, as we suppose, a single line, 
but a rope composed of at least four thousand strands.* But to feel all 
the wonder of this fact we must follow Leeuwenhoek in one of his calcu- 
lations on the subject. This renowned microscopic observer estimated that 
the threads of the minutest spiders, some of which are not larger than a 
grain of sand, are so fine that four millions of them would not equal in 
thickness one of the hairs of his beard — a tenuity utterly beyond the 
power of the imagination to conceive. Of the probable accuracy of this 
calculation you may any day in summer convince yourself, by taking one 
of the large diadem spiders (Kpeira Diadema), and, after pressing its 
abdomen against a leaf or other substance, so as to attach the threads to 
the surface—the same preliminary step which the spider adopts in spinning 
—drawing it gradually to a small distance. You will plainly perceive that 
the proper thread of the spider is formed of four smaller threads, and these 
again of threads so fine and numerous, that there cannot be fewer than a 
thousand issue from each spinner; and if you pursue your researches with 
the microscope, you will find that precisely the same takes place in the 
minutest species that spins. You will inquire what can be the end of 
1 Reaum. Mém. de Acad. de Paris, An. 1718. 211.—De Geer, vii. 187. See also 
Hoole’s Leeuwenhoek, i, 41.—t, 2. f. 20—22. Leeuwenhoek examined a spinner 
that was not so big as a common grain of sand, and the number of tubes issuing from 
it was more than a hundred. He affirms that, besides the larger spinners, in the 
space between them there are four smaller ones, each furnished with organs for 
spinning threads, but smaller and fewer in number. Latreille speaks only of a 
thousand spinners from each teat, and of six thousand threads from the whole— 
but he does not enter further into the subject. Nouv. Dict. d’ Hist, Nat. ii, 278. 
2 Mr. Blackwall, however, as the result of his examinations with microscopes 
of high powers, denies that spiders’ threads are composed of so many fine lines as 
Leeuwenhoek, Lyonnet, ‘Treviranus, &c., have supposed. He has not, he says, 
found that any lines ever issue, as they describe, from the minute apertures without 
projecting margins, situated between the papille or spinning tubes, which last alone 
he regards as the sole line-forming instruments, and the total number of these in the 
larger adult species of Zpeira, which are best provided with them, he does not esti- 
mate at much above a thousand, while in the common house spider they are below 
tour hundred, and in other species not above one hundred, and in some much fewer. 
As the statements of such careful and generally accurate observers as Reaumur, De 
Geer, Leeuwenhoek, Lyonnet, Treviranus, and other eminent naturalists, all in the 
main agreeing and confirming each other, ought not to be hastily set aside and 
without the fullest investigation, it has been thought best, without materially 
altering the text, simply to point out in the present note Mr. Blackwall’s different 
conclusions, and to refer the reader for the details on which they rest to his paper 
on the Mammule of Spiders in the 18th vol. of the Linnean Transactions, p. 210. 
