Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . ion as is emitted at one time, stretchedto the fullest extent that its great elasticity willpermit; and that the other is the result of suc-cessive supplies of the fluid, each successive emis-mission being marked by the formation of one ofthe knobs or globules. The threads of spiders silk are very fine, thesimple ones being about the thousandth of an inch June 1, 1868.] HARDWICKES SCIENCE-GOSSIP. 131 in thickness, the glutinous ones rather more. Ithas been generally stated that each
Hardwicke's science-gossip : an illustrated medium of interchange and gossip for students and lovers of nature . ion as is emitted at one time, stretchedto the fullest extent that its great elasticity willpermit; and that the other is the result of suc-cessive supplies of the fluid, each successive emis-mission being marked by the formation of one ofthe knobs or globules. The threads of spiders silk are very fine, thesimple ones being about the thousandth of an inch June 1, 1868.] HARDWICKES SCIENCE-GOSSIP. 131 in thickness, the glutinous ones rather more. Ithas been generally stated that each of these threadsis composed of a number of minute filaments,depending upon the number of tubules in themammulae from which they were spun. I cannothelp thinking, however, that such is not the case,and it certainly appears to me to be more naturaland more in accordance with the facts, as I haveobserved them, to suppose that the secretion fromthe numerous tubules coalesces on the surface ofthe mammulae to form a single drop of the viscusfluid, from which drop a homogeneous, and not acompound, thread is Fig. 124. Silk glands and tubules. It seems to me, if the thread was so complex ashas been supposed, that some observer would havesucceeded in isolating the various filaments; butas far. as I am aware this has never been existence, therefore, is certainly not proven,and is, I think, an unnecessary assumption. A single web often contains more than threehundred longitudinal and as many transversethreads: so elaborate is the seemingly simple neta spider sets to catcli its prey ! T. Graham Ponton, PERLEYS MEADOW DEPOSIT. rpHE following forms of Diatoms have been-*- detected in the deposit from Perleys Meadow,South Bridgton, Maine, which through the kind-ness of the Rev. E. C. Bolles, of Portland, has beensent to the Editor of this journal for distributionamongst its microscopical readers. It contains, aswill be observed, some very interesting species. Navicula
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