Therearethreevarieties，spiral，univalve，andbivalve。
　　Ineverysalt-paninthecountrythereisaspringofwaterononeside。
　　IcanremembernoexceptiontothisruleThewaterofthesespringsisbrackish，andcontainsthenitrateofsodaInoneinstancetherearetwosprings，andonemoresaltishthantheother。
　　Ifthissupplycamefrombedsofrocksaltthewaterwouldnotbedrinkable，asitgenerallyis，andinsomeinstances，wherethesaltcontainedinthepaninwhichthesespringsappearhasbeenremovedbyhumanagency，nofreshdepositoccursItisthereforeprobablethatthesedepositsofsaltaretheremainsoftheveryslightlybrackishlakesofantiquity，largeportionsofwhichmusthavebeendriedoutinthegeneraldesiccation。
　　WeseeaninstanceinLakeNgami，which，whenlow，becomesbrackish，andthisviewseemssupportedbythefactthatthelargestquantitiesofsalthavebeenfoundinthedeepesthollowsorlowestvalleys，whichhavenooutletoroutgoinggorge；andafountain，aboutthirtymilessouthoftheBamangwatothetemperatureofwhichisupwardof100Degwhilestronglyimpregnatedwithpuresalt，beingonaflatpartofthecountry，isaccompaniedbynodeposit。
　　Whenthesedepositsoccurinaflattufaceouscountrylikethepresent，alargespaceisdevoidofvegetation，onaccountofthenitratesdissolvingthetufa，andkeepingitinastateunfavorabletothegrowthofplants。
　　WefoundagreatnumberofwellsinthistufaAplacecalledMatlomagan-yana，orthe“Links“，isquiteachainofthesenever-failingspringsAstheyoccasionallybecomefullinseasonswhennorainfalls，andresemblesomewhatinthisrespecttheriverswehavealreadymentioned，itisprobabletheyreceivesomewaterbypercolationfromtheriversysteminthecountrybeyondAmongtheselinkswefoundmanyfamiliesofBushmen；and，unlikethoseontheplainsoftheKalahari，whoaregenerallyofshortstatureandlightyellowcolor，theseweretall，strappingfellows，ofdarkcomplexionHeatalonedoesnotproduceblacknessofskin，butheatwithmoistureseemstoinsurethedeepesthue。
　　OneoftheseBushmen，namedShobo，consentedtobeourguideoverthewastebetweenthesespringsandthecountryofSebituane。
　　ShobogaveusnohopeofwaterinlessthanamonthProvidentially，however，wecamesoonerthanweexpectedtosomesuppliesofrain-waterinachainofpoolsItisimpossibletoconveyanideaofthedrearysceneonwhichweenteredafterleavingthisspot：theonlyvegetationwasalowscrubindeepsand；notabirdorinsectenlivenedthelandscape。
　　Itwas，withoutexception，themostuninvitingprospectIeverbeheld；
　　and，tomakemattersworse，ourguideShobowanderedonthesecondday。
　　Wecoaxedhimonatnight，buthewenttoallpointsofthecompassonthetrailsofelephantswhichhadbeenhereintherainyseason，andthenwouldsitdowninthepath，andinhisbrokenSichuanasay，“Nowater，allcountryonly；Shobosleeps；hebreaksdown；countryonly；“
　　andthencoollycurlhimselfupandgotosleepTheoxenwereterriblyfatiguedandthirsty；andonthemorningofthefourthday，Shobo，afterprofessingignoranceofeverything，vanishedaltogether。
　　Wewentoninthedirectioninwhichwelastsawhim，andabouteleveno’clockbegantoseebirds；thenthetrailofarhinoceros。
　　Atthisweunyokedtheoxen，andthey，apparentlyknowingthesign，rushedalongtofindthewaterintheRiverMahabe，whichcomesfromtheTamunak’le，andlaytothewestofusThesupplyofwaterinthewagonshadbeenwastedbyoneofourservants，andbytheafternoononlyasmallportionremainedforthechildrenThiswasabitterlyanxiousnight；
　　andnextmorningthelesstherewasofwater，themorethirstythelittleroguesbecameTheideaoftheirperishingbeforeoureyeswasterribleItwouldalmosthavebeenarelieftometohavebeenreproachedwithbeingtheentirecauseofthecatastrophe；
　　butnotonesyllableofupbraidingwasutteredbytheirmother，thoughthetearfuleyetoldtheagonywithinIntheafternoonofthefifthday，toourinexpressiblerelief，someofthemenreturnedwithasupplyofthatfluidofwhichwehadneverbeforefeltthetruevalue。
　　Thecattle，inrushingalongtothewaterintheMahabe，probablycrossedasmallpatchoftreescontainingtsetse，aninsectwhichwasshortlytobecomeaperfectpesttous。
　　ShobohadfoundhiswaytotheBayeiye，andappeared，whenwecameuptotheriver，attheheadofaparty；and，ashewishedtoshowhisimportancebeforehisfriends，hewalkedupboldlyandcommandedourwholecavalcadetostop，andtobringforthfireandtobacco，whilehecoollysatdownandsmokedhispipe。
　　Itwassuchaninimitablynaturalwayofshowingoff，thatweallstoppedtoadmiretheacting，and，thoughhehadleftuspreviouslyinthelurch，wealllikedShobo，afinespecimenofthatwonderfulpeople，theBushmen。
　　NextdaywecametoavillageofBanajoa，atribewhichextendsfartotheeastwardTheywerelivingonthebordersofamarshinwhichtheMahabeterminatesTheyhadlosttheircropofcorn`Holcussorghum’，andnowsubsistedalmostentirelyontherootcalled“tsitla“，akindofaroidoea，whichcontainsaverylargequantityofsweet-tastedstarchWhendried，poundedintomeal，andallowedtoferment，itformsanotunpleasantarticleoffoodThewomenshaveallthehairofftheirheads，andseemdarkerthantheBechuanasTheirhutswerebuiltonpoles，andafireismadebeneathbynight，inorderthatthesmokemaydriveawaythemosquitoes，whichaboundontheMababeandTamunak’lemorethaninanyotherpartofthecountryTheheadmanofthisvillage，Majane，seemedalittlewantinginability，buthadhadwitenoughtopromoteayoungermemberofthefamilytotheofficeThisperson，themostliketheuglynegroofthetobacconists’shopsIeversaw，wascalledMoroaMajane，orsonofMajane，andprovedanactiveguideacrosstheRiverSonta，andtothebanksoftheChobe，inthecountryofSebituaneWehadcomethroughanothertsetsedistrictbynight，andatoncepassedourcattleovertothenorthernbanktopreservethemfromitsravages。
　　AfewremarksontheTsetse，or`Glossinamorsitans’，mayherebeappropriate。
　　Itisnotmuchlargerthanthecommonhouse-fly，andisnearlyofthesamebrowncolorasthecommonhoney-bee；theafterpartofthebodyhasthreeorfouryellowbarsacrossit；thewingsprojectbeyondthispartconsiderably，anditisremarkablyalert，avoidingmostdexterouslyallattemptstocaptureitwiththehandatcommontemperatures；inthecoolofthemorningsandeveningsitislessagileItspeculiarbuzzwhenonceheardcanneverbeforgottenbythetravelerwhosemeansoflocomotionaredomesticanimals；
　　foritiswellknownthatthebiteofthispoisonousinsectiscertaindeathtotheox，horse，anddogInthisjourney，thoughwewerenotawareofanygreatnumberhavingatanytimelightedonourcattle，welostforty-threefineoxenbyitsbite。
　　Wewatchedtheanimalscarefully，andbelievethatnotascoreofflieswereeveruponthem。
　　Amostremarkablefeatureinthebiteofthetsetseisitsperfectharmlessnessinmanandwildanimals，andevencalves，solongastheycontinuetosuckthecowsWeneverexperiencedtheslightestinjuryfromthemourselves，personally，althoughwelivedtwomonthsintheirHABITAT，whichwasinthiscaseassharplydefinedasinmanyothers，forthesouthbankoftheChobewasinfestedbythem，andthenorthernbank，whereourcattlewereplaced，onlyfiftyyardsdistant，containednotasinglespecimenThiswasthemoreremarkable，asweoftensawnativescarryingoverrawmeattotheoppositebankwithmanytsetsesettleduponit。
　　Thepoisondoesnotseemtobeinjectedbyasting，orbyovaplacedbeneaththeskin；for，whenoneisallowedtofeedfreelyonthehand，itisseentoinsertthemiddleprongofthreeportions，intowhichtheproboscisdivides，somewhatdeeplyintothetrueskin；
　　itthendrawsitoutalittleway，anditassumesacrimsoncolorasthemandiblescomeintobriskoperationThepreviouslyshrunkenbellyswellsout，and，ifleftundisturbed，theflyquietlydepartswhenitisfullAslightitchingirritationfollows，butnotmorethaninthebiteofamosquitoIntheoxthissamebiteproducesnomoreimmediateeffectsthaninmanItdoesnotstartlehimasthegad-flydoes；
　　butafewdaysafterwardthefollowingsymptomssupervene：
　　theeyeandnosebegintorun，thecoatstaresasiftheanimalwerecold，aswellingappearsunderthejaw，andsometimesatthenavel；
　　and，thoughtheanimalcontinuestograze，emaciationcommences，accompaniedwithapeculiarflaccidityofthemuscles，andthisproceedsuncheckeduntil，perhapsmonthsafterward，purgingcomeson，andtheanimal，nolongerabletograze，perishesinastateofextremeexhaustionThosewhichareingoodconditionoftenperishsoonafterthebiteisinflictedwithstaggeringandblindness，asifthebrainwereaffectedbyitSuddenchangesoftemperatureproducedbyfallsofrainseemtohastentheprogressofthecomplaint；
　　but，ingeneral，theemaciationgoesonuninterruptedlyformonths，and，dowhatwewill，thepooranimalsperishmiserably。
　　Whenopened，thecellulartissueonthesurfaceofthebodybeneaththeskinisseentobeinjectedwithair，asifaquantityofsoap-bubbleswerescatteredoverit，oradishonest，awkwardbutcherhadbeentryingtomakeitlookfatThefatisofagreenish-yellowcolorandofanoilyconsistence。
　　Allthemusclesareflabby，andtheheartoftensosoftthatthefingersmaybemadetomeetthroughitThelungsandliverpartakeofthedisease。
　　Thestomachandbowelsarepaleandempty，andthegall-bladderisdistendedwithbile。
　　Thesesymptomsseemtoindicatewhatisprobablythecase，apoisonintheblood，thegermofwhichenterswhentheproboscisisinsertedtodrawbloodThepoison-germ，containedinabulbattherootoftheproboscis，seemscapable，althoughveryminuteinquantity，ofreproducingitself，forthebloodafterdeathbytsetseisverysmallinquantity，andscarcelystainsthehandsindissection。
　　Ishallhaveby-and-bytomentionanotherinsect，whichbythesameoperationproducesinthehumansubjectbothvomitingandpurging。
　　Themule，ass，andgoatenjoythesameimmunityfromthetsetseasmanandthegameManylargetribesontheZambesicankeepnodomesticanimalsexceptthegoat，inconsequenceofthescourgeexistingintheircountryOurchildrenwerefrequentlybitten，yetsufferednoharm；andwesawaroundusnumbersofzebras，buffaloes，pigs，pallahsandotherantelopes，feedingquietlyintheveryhabitatofthetsetse，yetasundisturbedbyitsbiteasoxenarewhentheyfirstreceivethefatalpoisonThereisnotsomuchdifferenceinthenaturesofthehorseandzebra，thebuffaloandox，thesheepandantelope，astoaffordanysatisfactoryexplanationofthephenomenonIsamannotasmuchadomesticanimalasadog？
　　Thecuriousfeatureinthecase，thatdogsperishthoughfedonmilk，whereasthecalvesescapesolongastheycontinuesucking，madeusimaginethatthemischiefmightbeproducedbysomeplantinthelocality，andnotbytsetse；butMajorVardon，oftheMadrasArmy，settledthatpointbyridingahorseuptoasmallhillinfestedbytheinsectwithoutallowinghimtimetograze，and，thoughheonlyremainedlongenoughtotakeaviewofthecountryandcatchsomespecimensoftsetseontheanimal，intendaysafterwardthehorsewasdead。
　　Thewell-knowndisgustwhichthetsetseshowstoanimalexcreta，asexhibitedwhenavillageisplacedinitshabitat，hasbeenobservedandturnedtoaccountbysomeofthedoctors。
　　Theymixdroppingsofanimals，humanmilk，andsomemedicinestogether，andsmeartheanimalsthatareabouttopassthroughatsetsedistrict；
　　butthis，thoughitprovesapreventiveatthetime，isnotpermanent。
　　ThereisnocureyetknownforthediseaseAcarelessherdsmanallowingalargenumberofcattletowanderintoatsetsedistrictlosesallexceptthecalves；andSebituaneoncelostnearlytheentirecattleofhistribe，verymanythousands，byunwittinglycomingunderitsinfluenceInoculationdoesnotinsureimmunity，asanimalswhichhavebeenslightlybitteninoneyearmayperishbyagreaternumberofbitesinthenext；butitisprobablethatwiththeincreaseofgunsthegamewillperish，ashashappenedinthesouth，andthetsetse，deprivedoffood，maybecomeextinctsimultaneouslywiththelargeranimals。
　　TheMakololowhomwemetontheChobeweredelightedtoseeus；
　　andastheirchiefSebituanewasabouttwentymilesdowntheriver，MrOswellandIproceededincanoestohistemporaryresidence。
　　HehadcomefromtheBarotsetownofNalieledowntoSeshekeassoonasheheardofwhitemenbeinginsearchofhim，andnowcameonehundredmilesmoretobiduswelcomeintohiscountry。
　　Hewasuponanisland，withallhisprincipalmenaroundhim，andengagedinsingingwhenwearrivedItwasmorelikechurchmusicthanthesing-songeeeeee，aeaeae，oftheBechuanasofthesouth，andtheycontinuedthetuneforsomesecondsafterweapproached。