Maech 1, 1865.] 



SCIENCE-GOSSIP. 



65 



Spideks'_ Webs. — When we walk on a bright sum- 

 mer's morning alongside our garden walls, those who 

 have avery quick eyesight, or a common eyeglass,may 

 see tlie uet-Jike webs of the common garden spider 

 studded with minute drops glittering like dew ; but 

 as these do not evaporate when the sun advances, 

 they must be something more substantial. Under 

 the microscope, they will be seen arranged with 

 beautiful regularity on the cross-bars of the web 

 only. They are viscid to the touch ; the web, in this 

 way, being delicately lined, to take the smallest in- 

 sects striking against it. When mounted as objects 

 for the microscope, as they often are, the surprising 

 fact at length grows upon us, that these minute 

 beads of fluid, though kept in dry rooms and cabinets 

 for months, and even jears, never dry up, and apija- 

 rently never change. What makes up these little 

 persistent globules, and how are they arranged so 

 evenly ? If a newly-spun web is brought down upon 

 a slip of glass, and made to adhere to it, the viscid 

 drops spread upon the surface, and show a little 

 imcleus or core of gum in the centre of each ; it will 

 be seen too, that the viscid fluid surrounds not only 

 the cores but the whole line of the cross-bar, being 

 collected only more copiously on the little cores 

 dotted along it, and which have served as centres of 

 attraction ; but for these, the fluid, when poured 

 upon the web, would have run into larger drops and 

 fallen to the ground, or at least have been unequally 

 distributed. The cores adlicre but loosely to the 

 web, and may be easily moved with a fine mounted 

 hair; and, in doing so, it will be found that the 

 cross bars, unlike the other _ lines of the web, are 

 highly elastic. If the fresh viscid drops (still uuder 

 the microscope) are made to touch blue litmus paper, 

 they instantly sink into and redden it. The com- 

 mon solution of chloride of calcium also reddens the 

 test paper ; and it seems not unlikely that to the 

 presence of this, or some other highly deliquescent 

 salt, the undrying nature of the viscid fluid may be 

 due. This spider's web is a complicated structure, 

 and is composed of various materials : the side and 

 radial lines of a fluid, which, like silk, hardens as it 

 leaves the spinneret ; the elastic cross bars which 

 never harden, the Little cores of transparent guni 

 dotted along them, and the saline and viscid fluid 

 poured over all ; and yet, upon close examination of 

 the spinneret, it is comprehensible that the web 

 should be completed at one operation, that is, that 

 no part of it should be gone over twice. _ A view of 

 the insect at her work might clear up this point, and 

 our fern-cases might, perhaps, be turned to further 

 good aecoimt for this purpose. But the spiders 

 have now gone into winter quarters, and we must 

 wait another summer. Meantime these few facts 

 and queries may show us that there is something 

 yet to learn of this curious and beautiful structure. — 

 S. S., ill Gardener's Chronicle. 



Lists of Acaul— Can you refer me to complete 

 list of Jairif—R. B. 



Koch's continuation of Hahu's Arachniden ; and 

 Koch's series of Apterous Insects in Henrieh 

 Schaffer's continuation of Panzer's German Insects, 

 contain the most complete series of Acari. An 

 excellent summary is given in AValckenaer's Hist. 

 Nat. Ins. Aptcres, in the Suites a Buflbn, vols. 3 

 and 4.—/. 0. IF. 



Embryonic Development. — All organs spring 

 from a blastema, which is primarily composed of 

 sareode, and gradually assume their special features 

 afterwards ; but when first perceived they differ only 

 in size from the adult forms. The embryo, in point of 

 fact, is a miniature of the perfect being. In the course 

 of development every animal exhibits very strange 

 phenomena, both as to its entire economy, and in 

 regard to special organs ; and this is particularly 

 the case with reference to mammalia. Dailj', ay, 

 even hourly, the scene is changed, and this unsettled 

 condition applies not only to essential, but also to 

 merely accessory organs. One might fancy that 

 nature was feeling her way to a conclusion. Here 

 may be seen cavities being gradually partitioned off, 

 divided, as it were, into distinct chambers, or drawn 

 out in the form of canals, which, in their turn, are 

 often refilled witii solid matter, and converted into 

 ligaments ; in another locality we observe previously 

 solid masses transformed into cavities, membranous 

 folds being rolled out into tidies, isolated portions of 

 tissue drawn together to form a continuous organ, 

 or even a mass hitherto entire, being cut up into 

 several new structures. Not only the form and 

 proportions, but the relations also of the various 

 mechanisms are being momentarily altered. Parts 

 which at first had been closely related separate from 

 each other and become distinct, and organs which 

 had heretofore been distant from each other form 

 ties of close alliance. Those apparatus whose 

 ofiice is a temporary one rapidly increase in size, 

 acquire an enormous volume, and eventually dis- 

 appear altogether. _ Others are arrested in their 

 growth at a certain period, and, though all the 

 organs in their neighbourhood continue their de- 

 velopment, yet they remain in their primitive con- 

 dition, and may be detected in the adult, where 

 they testify to a former state of things very different 

 from the existing one. Thus we perceive that the 

 history of embryonic development may be summed 

 up as consisting in incessant transformations and, 

 constant activity. — Quatref ages' Metamorphoses, trans- 

 lated by Dr. Lawson. 



The Ikrationale oe Speech.— To the minute 

 philoso]3her, who holds that things are strange in 

 ]5roportion to their commonness ; that the fit attitude 

 tor the human mind is that of habitual wonder; and 

 that true science, so far from explaining phenomena, 

 only shows that they are inexplicable, or likely to 

 be so, not merely as to their final, but as to their 

 proximate causes ; — to him, I say, few things seem 

 more miraculous than human speech. He has not 

 time to ascend to the higher question of the meta- 

 physics of language ; not even to that first question, 

 How did the human race ever make the surprismg 

 discovery that objects might be denoted by symbols, 

 by names ; and how did they comnumicate that 

 discovery to each other ? PuzzHng as that question 

 is, he is stopped short of it in wonder by a puzzle 

 equally great — by the mere physical fact of articula- 

 tion, which man has in common with the parrot and 

 the daw. — The Irrationale of Speech. 



Mounting Polyzoa. — A correspondent desires 

 to be inibrmed of any process by means of which he 

 may be able to mount specimens of the Poltizoa in 

 their expanded state. He has sought the infornia- 

 tion in various text-books, and tried several methods, 

 alike without success. 



