Document R2pQKdEkdjN14QqrMd66rv2Za

n 0) too Not only the fork of the tail but also the body of the cerearia ean produoe a worker propulsion end a stronger baekwavd thrust (Fig. 2b>. In this ease the body works on the principle of the flih-tail. but bonding is target)' reptaoed by oselllatlon around a joint-like area. As the oeroaria ewhns forward (Fig. le and d) the folded fork branches function like an elastie tail fin. The connexion between body and tail has lost its flexibility and is now actually rigid. As a result of nsw properties of resistance e wave passes along tbs oeroaria from the body to the tail end with all striated muscles squally aetivs (Fig. le and rf). TVs results in propulsion. The maximum speeds for animals swimming backwards or forwards are 1*4 mm/eee 5 the distanoe covered in 1 tee oorresponds to about three body lengths. Swimming backward and forward by means of an adjustable forked tail has bean reproduced in a model (built by H.*Q. Beokmann and celled "Cerearia I"). A forked tall made of rigid material with a joint as in Fig. 1/ is sufficient to produoe baokward movement which oan be converted to propulsion and vios versa, even in the model, by folding oeokwards the branohes ofthe transverse oar Wade and by retaining the limited range of the joint (Fig. Iff). Models of this Kind eould perhaps be applied te mixing tasks and driving mechanisms in engineering. Q. Qiumrs Paresitologiosi Institute, \V. Honoust H. DnAosa Farbwerke Hoschst AG, II Frankfurt (Main)-Hftohat. lltMlvri DswmSsr It, ItMs rsvfcwS ftbrserr t. 1M7. Dteruit In Efgihsll Weight In Certain Birds of Prey Tut inoidenoe of broken eggs in nests of peregrine faJoon Fain prrtpinW) sparrowhewk Aocipittr nieti and goldon eaglo dfuila chrysorios in Britain has increased con siderably since 1000. In 100 peregrine eyries examined in I904-00, there wore only threo instances of egg breakage, eompared with forty-seven in 100 eyries examined in I00I-M. Two of thirty-flvo goldon eagle eyrios examined in 1080-00 contained broken eggs, compared with twelve out of forty -sight examined in 1051-01. Ons breakage was fohnd in twenty-four sparrowhawk nests in 1948-00, but sight in twenty-seven iwsts in 1051-00. Peregrines have basil witnessed catini (.heir own eggs*, and most rseont egg breakages in all thru** species appeared to involve parental destruction. Itplwl thloknoos was investigated by reassuring weight and sisc of blown eggs of varying ago, using NATURE. VOL. 2l5^jULY . !M7j speoimont cleanly emptied through a hole not oxeooding 7 mm in diameter, thus rejecting hoavily incubated eggs. In poregrmo and sparrowhawk, eggshell woight/stso ratio docresscd significantly and suddenly in 1940-00, and has not reoevered. Since 1947, ths only "normal" peregrine oggshellt were four of ths seven availablo from tho East Highlands. Aftsr 1940, sparrowhawk eggshells from Surrey were significantly lighter than those from Cumberland, Dorset and Hampshire. Goldon eagle eggshells from West Ismland are slightly yet very signifloantly lighter but East Highland eggshells rerosin nnohonged. Fewer golden eagle eggs wore available, but change during 194V0G is again indicated. The eggshells as measured consisted largely of calcium carbonate (about 90 per oent in "normal" eggs), the remaining fraotion being shell protein1, adherent shell membranes, and residual film of contents. The decrease in eggshell weight has involved mainly the calcium carbonate fraotion. Decrease in shell thickness rather than density is implied, but this has not been measured directly. Thickness of eggshells and production of eggs vary according to diet (especially calcium) and condition in poultry} eggshell thickness is also genetically influenced, and diminished by disease and increasing age1. Certain chemicals, for example sulphanilamide*. cause decrease in eggshell thickness, as can stress; severe fright can stop poultry laying for a time. Occasional thin-shelled eggs may be laid by any wild bird speeies, but before 1946, mean eggshell weight and size for clutches from the same female raptor, year by year, were fairly constant, though weight/sice of eggshells within one clutch was less con sistent. Decrease in eggshell weight in peregrine and sparrow, hawk was synchronous, rapid and widespread. It occurred in successive clutches of the same female peregrines at four different eyrios, but three other females laid st least ons dutch of normal woight after they had produced light eggs. General ageing or gonetie shill in the population are thus not likely to be involved, while the synchronous effect on three raptors with different ecology and distri butions, and the varying geographical response, make disease an unlikely explanation. Decrease of calcium carbonate for eggshell formation could result from reduced food consumption, but no decline in available food supply for those raptors was known in 1940-00. Loss of hunting efficiency could oauss an effective food shortage, or change in metabolic regula tion eould induoe internal shortage of calcium, without less food being consumed. A different possibility is premature extrusion of eggs, known in poultry (personal communication from C. Tyler). 8ome physiologies! change evidently followed a wide spread and pervasive env ironmental ohange around 1045 47. Increasing radioaetlvo contamination fails to account for geographical variations in eggshell change, whereas these match tho developing regional pattern of contamina tion by chemioal pollutants during this period. Among urban-industrial pollutants, one waste product in smoke, the persistent polychlorinated biphenyl (POB), has been found in tissues of fish, eagles and humans in flwadsn, and was first detected in 1944 in an eagle*. There was a notable boom in organic insecticides, fungicides and herbi cides. containing chlorine, mercury, phosphorus and sulphur after 1945, and environmental contamination by pereistmt residues has boon widespread*. British pere grines, aparrowhawks and golden eagles have shown wide spread contamination by pp' DDT, pp' DDE, y-BHC, dieldrin and heptachlor epoxide'-*. Tlw introduction of MGNS 087.306 NATURE. VOL. 219. JULY 9. IN7 209 Tton(rr) Chctortyrmfttfro law ttMttl t%4 tut*** ttsiUih IWOmmW. set Mirwnmt enaMli from o<htr diitriHa DDT Into general uao (About 1943-44) coinoided olosely with onset of tho tcathcll change. DMdria, aldrin And htptsnhlnr appcarodlbyr Intor And, like DDT ondy-BHC, have boon oood cRtwalvety over tince. COntominotion of biido by paniiionl ormmo-mereiiry compound* hao rpooirod Itttto ottontkon In Britain, but in Swodon tlw introduction of Vhm m toed dressings paralleled tho eubstaatlal inoroooo in meroury eontont of raptor tlwuM during tho 1940* (ref. 10). Calcium raotoboliom in bird* it controlled by oeatrogon Mid parathyroid honnono1, nnd i* thua potentially oomitivo to any ohoraionl disturbing hormono regulation. JaibriM11 hoo demonstrated a significant eorrolotioa between intako of pp' DDT by th* Bengalese flnoh LoncAuro Mriata ond delay in ovulation, ond interprets thio u a hormonal O0BOt. Oho dltidooarbnmoto ninglcide afTeote eggshell Ihtehn-- in poultry1*, but it non-peraistont ond or un known relevance to raptor*. Tho tiim oorrolation between decrease in eggshell weight ond Inarenoo In egf-breokege suggeeta a oaueal eon- nexion. In the peregrine end golden eagle there it alto geo graphical correlation, for in the Seat Highland* daeraate ui eggshell weight it slight or unknown and egg breakage unuauol. Eating egga is probably an Instinctive adaptive reeponee to unfavourable eireumataneee arising efter laying, and seldom invoked before 1046. Other bird aptoiea normally eat or destroy their damaged eggs", and lighter raptor eggs are probably more prone to acci dental damage than^norraol" egga. Yet, often, raptors have evidently destroyed undamaged eggs, porhapt in response to a calcium "hunger''. Domoetio jowl which have broken and eaten an egg often develop an incurable appetite for their eggs. White calcium is obviously impli cated, in several raptor instance* the egg contents had boon eaton and most of tbs shell left. Other bird species in which egg-breaking it unusual (hobby /fot lubbvUo, merlin F. witmkm'w, burned Bette butte, carrion erow Corvee eoroni, golden plover Oboradriee apricariu*, greenehank Tringa tubularia, guillemot Uria oaJpe, and ratorbill Alca fordo) show no MONS 087307 SIO NATURE. VOL. 2)9. JULY 9. 1907 g4 RKS4 T*Mr l. lutamni or i *a#w m 1000-40 104T-07 n or nun atmss mrqh, icoo-iftsr 3ffID surat* length (mm) bMMltti(MM) '"agr'' xswat sSKM Wiwote 4Msla 1*9 MtamasSseilO 1000-40 1047-07 1000-40 1047-47 1000-40 1047-07 I'll 1-00 .;t u Ml 111 l-ftt 1.071 9,000 114 I 71 m 1U 154 i,m i,m 1 41 MO OaOowaf ImSm Ik ibm 107 Ml 14S7 lM lilt i.in i,m 4.151 4.501 141 I II <0 001 <0 001 AasWva C.M4K. HlfMreOs 107 14 1417 14-45 4,551 4.000 111 tit -- . * That* OMMMUrtt aho* * IDekirttr doaa rrisUonahlp to aortas uut of the enahrite to )vatify Mini the more ilrnph derived len|lh breadth (in#) moo Index of alM. t The la pms*a4 to indicate thirkntaa, hot II eotM alto indtrate danattr ofasphalt. ehang* in eggshell weight. In kestrel F. tinnuneuhts and revolt Cerrw aoror, the egg* of aome individual* show a light drorenor, but not the whole population cample*. For th* *poio* ixamintd, freoueney of egg-breekege, Milo of deoroaoo in eggshell weight, eubsequeni *tetu* of brooding population, and exposure to persistent organic poeUoldoo are oorrolatod. Tito possibility that there phenoraona ore link* In a oauoal chain io boing inveotigatod. Recovery of ioeajly depleted population* of peregrine began In 1948 and eontinued for reveral yearo after eggimHi beoame lighter and ogg eating frequent, oven in diotriota, ouoh at Dorset, whore both onangoo were obviouo. Population "oreaheo" In peregrine end sparrowhawk after 1968 probably involved greatly inoreared adult mortality, but lator fkotoro oontributing to low breeding I thank D. Notharooto-Thompaon, N. W. Moore, I. Froott, B. Blosard, C. J. O. Harrieon, I. Lyotor, C. W. Banoon, R. Btokoe, C. Boat, R. Wsgstaffe, A. Tyitan, A. D. and M- Horritl, J. P. Dempster and Mia* B. BatohoJor for their help. D. A. Ratcliff* The Nature Conoervanoy, Monks Wood Experimental Station, Abbott Rlpton, Huntingdon. IUmIvU Slor Mvtord Ma>- II, 1MT. * kolHWh. I). A., grft. 9M, *1.99(ISM). * Trier, C., cod Onk*. r. M., J. Sri. 9W Awfe., 0, tOI (100*). ' Murk*, t. D.. AW*n PSprMcpp (CorsWI Cnlv. 7m. Xsw Tork. 1054). * Tjtat.C., Ml. J. Xntrft.., m (ISM). ` Janars, a, Km 8ti,, . ait (1M0K * Vasrr, k. W.. Ml. gtH, 9m. Me*.. Oxthrd (IMS). * XalHIft. D, A., MM JMr.lt. MdttO). * Tmn, l.. vela irtnreUe MUNWawa (M (he rn*m). * Lactic, 3. D,, ud XttaMflft, ft, A.. 9r*. HHt, ft, 00 (1004). Jolmak, A.. Btfitned. B., oed Waatwmsah, T., 045m, IT. 71 " JsgariHtV 3.. JWr.it*. 9*0 (1*97). '* Here. D.. A*. KM. Afcnfe. 50/00,101 (IHt). SHhpsM.Tham|aii( C,^d Kathmofc-Tfcompaoii, D.. Ml. Mi, 99. abrasive diok*. The investigolioi) hen* reported followed the almost complete failure of a rubbl'd sample of beetroot seed* to germinate in a field in which different rubbed ample of the un* eultivar (`Detroit Globe1), sown at the tame time, germinatod satisfactorily. Neither sample contained any obviously damaged reed* end no damage we* found when embryos excised from imbibed seed* were examined under the microscope. Natural (unrubbed) toed* from the same sources (Lot 1, good; Lot 2, bad) were later obtained. In a series of laboratory experiments we found that: (1) Germination of unwashed seeds can bo depressed by insufficient moisture (Fig. I A). (2) When beetroot seeds ere washed and then immediately placed on wet filter paper scarcely any will germinate; out if they are washed, dried and then placed on moist filter paper they germinate well (Table 1). (9) Similarly, germination can be depressed when seeds ere placed on a substrate which is oven slightly wetter than necessary (Fig. 1); this effect is particularly pronounoed with unwashed seeds (Fig. IX) but can be alleviated by adding mall quantities of hydrogen peroxide (Table 2). Warburg reipirometor results show that the respiration of beet seeds Io appreciably suppressed in a slight excess of water. (4) Natural seeds from Lot 2 germinate at least es satis factorily as seeds from Lot 1, but nibbing depresses the performance of reads from Lot 2, though not of there from Lot 1 (Fig. IB). (5) Shaking the reeds for 48 rein in a glass bottle has an effect on germination similar to that Table 1. srrscT or pxnse mn wifpxo (minuet Xstsrsl Drying 14 ml. water per 4Mt 4* IVi net termination 15 h on Ihrte tHutsu Xe. 1 Molituro Sensitivity, Mechanical Injury and Glbberellln Treatment of Beta vulgaris Seeds "RreeixO" ("shearing") io a mechanical process used to separate tie fruit dustor* of Bala raiprii L. (sugar beet or beetroot) into more or lore oven-tired segments, eaoh with one or two seeds, by grinding away some of the herd Home ourrAinding the reed* with an assembly of Tabic S. trrtcr or mtpkoocx rrnoxmt ns aesmisatios or JWa mfeofii t. (pEreorr) assoc Hydros** iwrbxhfe In Per ornt irrmlsattos gemination wafer Katoral aceda Xublnt aeedi Mean F-0-01. 01 95 so ;; 74- 59 Mctfc wore placed In ft n* Olcmrfer Pclrl 41a* on (op of rUrntanMciooacdWrtvdkcsotstnytn*p-e-.XJosf.roe1tstSIaMaluasrrs. ps9p0r*nCw. ithlo9rmal.ewUaaffeerrtfoorrr natural so* i tawdreUre nl. for of ttw MONS 08730b iip s in iiiiif i. . t s e a im iM i* U**| .m t*xf