296 PROCEEDINGS OF SOCIETIES. 



Eeading Microscopical Society.* 



October 13. — Captain Lang exhibited mounts of webs of three 

 kinds of spider ; the first that of Epeira diadema ; the second of 

 an undetermined species, as unfortunately he coukl never find the 

 owner at home (though the web was renewed each night, after being 

 destroyed) ; and the third also unknown, being an old bought slide. 



All three were furnished with the viscid beads so well known on 

 the concentric threads of Epetra ; but those on the third slide were 

 much larger, and the threads appeared to be not spiral or concentric ; 

 whilst the arrangement of beads on the second was very difi"erent and 

 peculiar. This web was not geometrical. 



Till lately it was generally considered that the spider, after form- 

 ing its web, went over it again, adding the viscid drops or beads ; but 

 the late Richard Beck exploded that fallacy, by simply watching 

 (under a microscope) an Epeira making its web, when he saw that the 

 thread, after emission, ran into beads by molecular attraction. 



Captain Lang, however, though accepting this general fact, con- 

 siders that two of the three pairs of spinnerets are employed in the 

 formation of the thread; the simple line issuing from one pair whilst 

 tlie other pair varnishes it with a viscid secretion running into beads by 

 molecular attraction, as saliva will on a hair passed between the lips. 

 The second slide seemed to prove this ; for, whereas in the Epeira web 

 the beads were seen to be arranged singly along the line, and might, 

 therefore, be produced according to Mr. Beck's theory, in that par- 

 ticular slide the beads are grouped in grape-like bunches on a firm 

 thread. The threads of both species are perfectly dry, and not viscid 

 between the beads. If the web of an Epieira is caught on a slip of 

 glass its form is entirely destroyed ; the fluid viscid drops being as it 

 were blotted out, whilst in the second kind of web the threads, with 

 their harder grape-like bunches, will remain distinct and uninjured. 



In Epeira the four external sj^innerets are arranged in two pairs, 

 each pair containing tubuli differing from those of the other, so that 

 though the glands of these two pairs of spinnerets are similar, it 

 seems reasonable to suppose that they are used for different purposes. 



Captain Lang thinks that but one pair of these exterior spinnerets 

 is employed in forming the concentric line, which is varnished over, 

 as it runs out, by the third interior pair of spinnerets, fiu'nished with 

 a viscid secretion from a totally different set of glands. There are 

 other offices for which the other pair of exterior spinnerets with their 

 different tubuli may be needed, and also where no viscidity of thread 

 may be required, as in the formation of the radial lines, which are 

 thicker and more elastic ; or for that of the web with which the insect 

 victim is swathed in a mummy-like shroud. 



From slides showing the attachments of the Epeira's radial thread 

 it would appear that the spider uses its spinnerets as a painter does 

 his brush ; the very delicate threads issuing from each tubule being 

 dashed against the surface, formed into an entangled mass of loops, and 

 then drawn out into one compound, though practically simple thread. 

 ♦ Report supplied by Mr. B. J. Austin. 



