90 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



sufficient power to separate the beads, is yet more difficult ; and the exces- 

 sive rapidity with which the spiral lines are spun forms the greatest ob- 

 stacle of all to a successful observation. 



However, I was able to obtain the required favorable conditions by 

 colonizing a number of spiders of various species, especially the Basket 

 Argiope, upon honeysuckle vines which cover a fence and arbor in my 

 yard. I thus learned that the spiral thread issues apparently from the an- 

 terior spinnerets and that they issue as a pure white line, -the whiteness 

 being equally distributed over the thread, and presenting quite a contrast 

 with the bluish whiteness of the lines which are used for the radii and 

 foundation. Frequently I saw a minute globule of glistening liquid ap- 

 pear on the emitted thread at the space of four or five millimetres from the 

 spinning tubes; but this was immediately spread along the line by the 

 brushing movement of the fourth leg, or naturally distributed itself. 



After various efforts to observe the character of the line as it issued 

 from the spinning spools, in which I was only partially successful on ac- 

 count of the rapid movements of the spider, I fixed my attention upon a 

 selected portion between two radii which had just been attached ; and 

 then upon the next and the next string toward the moving spider. By 

 using a magnifying glass of moderate power I was enabled to see that 

 in a short space, varying in different spiders, and indeed varying on the 

 web spun by the same spider, the process of crystallization, as perhaps I 

 may call it, or aggregation, began. Here and there along the 

 Breaking j me there would first show points of roughening in the out- 

 B , line. From these several centres, on either side, the roughened 

 condition would spread, presenting somewhat the appearance of 

 the spiral threads of a screw. Gradually the detached points assumed 

 figures more or less oval, and subsequently the globular or subglobular 

 forms which are most common in the beads. By shifting the lens I could 

 see this process going on all along the strings most recently spun. At 

 one end of a string or interradial the beads would be forming, while 

 at the extremity nearest the spider's spinnerets the line would be perfectly 

 smooth. 



Beyond the string under observation the parts spun a few moments 

 earlier were covered with beads of normal shape. This observation was 

 repeated a number of times, and these matters are now definitely settled : 

 first, that the viscid material is placed upon the spiral thread contempo- 

 raneously with its emission; second, after a string has been placed be- 

 tween its two radii it naturally undergoes the process of aggregation 

 common to viscid liquids in like position; and finally, it assumes with 

 greater or less rapidity the forms of oval or globular beads gathered 

 around the thread. 1 



1 The two sorts of material are evidently secreted from two different glands, and per- 

 haps also emitted through different spinning tubes. 



