ops　of　these　barrel…shaped　plants。　　He　scooped　out　soft　pulp；　and　with　stone　and　hand　then　began　to　pound　the　deeper　pulp　into　a　juicy　mass。　　When　he　threw　this　out　there　was　a　little　water　left；　sweet；　cool　water　which　man　and　horse　shared　eagerly。　　Thus　he　made　even　the　desert's　fiercest　growths　minister　to　their　needs。
  But　he　did　not　halt　long。　　Miles　of　gray…green　spiked　walls　lay　between　him　and　that　line　of　ragged；　red　lava　which　manifestly　he　must　reach　before　dark。　　The　travel　became　faster；　straighter。　And　the　glistening　thorns　clutched　and　clung　to　leather　and　cloth　and　flesh。　　The　horses　reared；　snorted；　balked；　leapedbut　they　were　sent　on。　　Only　Blanco　Sol；　the　patient；　the　plodding；　the　indomitable；　needed　no　goad　or　spur。　　Waves　and　scarfs　and　wreaths　of　heat　smoked　up　from　the　sand。　　Mercedes　reeled　in　her　saddle。　　Thorne　bade　her　drink；　bathed　her　face；　supported　her；　and　then　gave　way　to　Ladd；　who　took　the　girl　with　him　on　Torre's　broad　back。　　Yaqui's　unflagging　purpose　and　iron　arm　were　bitter　and　hateful　to　the　proud　and　haughty　spirit　of　Blanco　Diablo。　For　once　Belding's　great　white　devil　had　met　his　master。　　He　fought　rider；　bit；　bridle；　cactus；　sandand　yet　he　went　on　and　on；　zigzagging；　turning；　winding；　crashing　through　the　barbed　growths。　The　middle　of　the　afternoon　saw　Thorne　reeling　in　his　saddle；　and　then；　wherever　possible；　Gale's　powerful　arm　lent　him　strength　to　hold　his　seat。
  The　giant　cactus　came　to　be　only　so　in　name。　　These　saguaros　were　thinning　out；　growing　stunted；　and　most　of　them　were　single　columns。　Gradually　other　cactus　forms　showed　a　harder　struggle　for　existence；　and　the　spaces　of　sand　between　were　wider。　　But　now　the　dreaded；　glistening　choya　began　to　show　pale　and　gray　and　white　upon　the　rising　slope。　　Round…topped　hills；　sunset…colored　above；　blue…black　below；　intervened　to　hide　the　distant　spurs　and　peaks。　　Mile　and　mile　long　tongues　of　red　lava　streamed　out　between　the　hills　and　wound　down　to　stop　abruptly　upon　the　slope。
  The　fugitives　were　entering　a　desolate；　burned…out　world。　　It　rose　above　them　in　limitless；　gradual　ascent　and　spread　wide　to　east　and　west。　　Then　the　waste　of　sand　began　to　yield　to　cinders。　　The　horses　sank　to　their　fetlocks　as　they　toiled　on。　　A　fine；　choking　dust　blew　back　from　the　leaders；　and　men　coughed　and　horses　snorted。　　The　huge；　round　hills　rose　smooth；　symmetrical；　colored　as　if　the　setting　sun　was　shining　on　bare；　blue…black　surfaces。　But　the　sun　was　now　behind　the　hills。　　In　between　ran　the　streams　of　lava。　　The　horsemen　skirted　the　edge　between　slope　of　hill　and　perpendicular　ragged　wall。　　This　red　lava　seemed　to　have　flowed　and　hardened　there　only　yesterday。　　It　was　broken　sharp；　dull　rust　color；　full　of　cracks　and　caves　and　crevices；　and　everywhere　upon　its　jagged　surface　gew　the　white…thorned　choya。
  Again　twilight　encompassed　the　travelers。　　But　there　was　still　light　enough　for　Gale　to　see　the　constricted　passage　open　into　a　wide；　deep　space　where　the　dull　color　was　relieved　by　the　gray　of　gnarled　and　dwarfed　mesquite。　　Blanco　Sol；　keenest　of　scent；　whistled　his　welcome　herald　of　water。　　The　other　horses　answered；　quickened　their　gait。　　Gale　smelled　it；　too；　sweet；　cool；　damp　on　the　dry　air。
  Yaqui　turned　the　corner　of　a　pocket　in　the　lava　wall。　　The　file　of　white　horses　rounded　the　corner　after　him。　　And　Gale；　coming　last；　saw　the　pale；　glancing　gleam　of　a　pool　of　water　beautiful　in　the　twilight。
  Next　day　the　Yaqui's　relentless　driving　demand　on　the　horses　was　no　longer　in　evidence。　　He　lost　no　time；　but　he　did　not　hasten。　　His　course　wound　between　low　cinder　dunes　which　limited　their　view　of　the　surrounding　country。　　These　dunes　finally　sank　down　to　a　black　floor　as　hard　as　flint　with　tongues　of　lava　to　the　left；　and　to　the　right　the　slow　descent　into　the　cactus　plain。　　Yaqui　was　now　traveling　due　west。　　It　was　Gale's　idea　that　the　Indian　was　skirting　the　first　sharp…toothed　slope　of　a　vast　volcanic　plateau　which　formed　the　western　half　of　the　Sonora　Desert　and　extended　to　the　Gulf　of　California。　　Travel　was　slow；　but　not　exhausting　for　rider　or　beast。　　A　little　sand　and　meager　grass　gave　a　grayish　tinge　to　the　strip　of　black　ground　between　lava　and　plain。
  That　day；　as　the　manner　rather　than　the　purpose　of　the　Yaqui　changed；　so　there　seemed　to　be　subtle　differences　in　the　others　of　the　party。　　Gale　himself　lost　a　certain　sickening　dread；　which　had　not　been　for　himself；　but　for　Mercedes　and　Nell；　and　Thorne　and　the　rangers。　　Jim；　good…natured　again；　might　have　been　patrolling　the　boundary　line。　　Ladd　lost　his　taciturnity　and　his　gloom　changed　to　a　cool；　careless　air。　　A　mood　that　was　almost　defiance　began　to　be　manifested　in　Thorne。　　It　was　in　Mercedes；　however；　that　Gale　marked　the　most　significant　change。　　Her　collapse　the　preceding　day　might　never　have　been。　　She　was　lame　and　sore；　she　rode　her　saddle　sidewise；　and　often　she　had　to　be　rested　and　helped；　but　she　had　found　a　reserve　fund　of　strength；　and　her　mental　condition　was　not　the　same　that　it　had　been。　　Her　burden　of　fear　had　been　lifted。　Gale　saw　in　her　the　difference　he　always　felt　in　himself　after　a　few　days　in　the　desert。　　Already　Mercedes　and　he；　and　all　of　them；　had　begun　to　respond　to　the　desert　spirit。　Moreover；　Yaqui's　strange　influence　must　have　been　a　call　to　the　primitive。
  Thirty　miles　of　easy　stages　brought　the　fugitives　to　another　waterhold；　a　little　round　pocket　under　the　heaved…up　edge　of　lava。　There　was　spare；　short；　bleached　grass　for　the　horses；　but　no　wood　for　a　fire。　　This　night　there　was　question　and　reply；　conjecture；　doubt；　opinion；　and　conviction　expressed　by　the　men　of　the　party。　But　the　Indian；　who　alone　could　have　told　where　they　were；　where　they　were　going；　what　chance　they　had　to　escape；　maintained　his　stoical　silence。　　Gale　took　the　early　watch；　Ladd　the　midnight　one；　and　Lash　that　of　the　morning。
  They　day　broke　rosy；　glorious；　cold　as　ice。　　Action　was　necessary　to　make　useful　benumbed　hands　and　feet。　　Mercedes　was　fed　while　yet　wrapped　in　blankets。　　Then；　while　the　packs　were　being　put　on　and　horses　saddled；　she　walked　up　and　down；　slapping　her　hands；　warming　her　ears。　　The　rose　color　of　the　dawn　was　in　her　cheeks；　and　the　wonderful　clearness　of　desert　light　in　her　eyes。　　Thorne's　eyes　sought　her　constantly。　　The　rangers　watched　her。　　The　Yaqui　bent　his　glance　upon　her　only　seldom；　but　when　he　did　look　it　seemed　that　his　strange；　fixed；　and　inscrutable　face　was　about　to　break　into　a　smile。　　Yet　that　never　happened。　　Gale　himself　was　surprised　to　find　how　often　his　own　glance　found　the　slender；　dark；　beautiful　Spaniard。　　Was　this　because　of　her　beauty？　he　wondered。　　He　thought　not　altogether。　　Mercedes　was　a　woman。　　She　represented　something　in　life　that　men　of　all　races　for　thousands　of　years　had　loved　to　see　and　own；　to　revere　and　debase；　to　fight　and　die　for。
  It　was　a　significant　index　to　the　day's　travel　that　Yaqui　should　keep　a　blanket　from　the　pack　and　tear　it　into　strips　to　bind　the　legs　of　the　horses。　　It　meant　the　dreaded　choya　and　the　knife…edged　lava。　　That　Yaqui　did　not　mount　Diablo　was　still　more　significant。　Mercedes　must　ride；　but　the　others　must　walk。
  The　Indian　led　off　into　one　of　the　gray　notches　between　the　tumbled　streams　of　lava。　　These　streams　were　about　thirty　feet　high；　a　rotting　mass　of　splintered　lava；　rougher　than　any　other　kind　of　roughness　in　the　world。　　At　the　apex　of　the　notch；　where　two　streams　met；　a　narrow　gully　wound　and　ascended。　　Gale　caught　sight　of　the　dim；　pale　shadow　of　a　one…time　trail。　　Near　at　hand　it　was　invisible；　he　had　to　look　far　ahead　to　catch　the　faint　tracery。　Yaqui　led　Diablo　into　it；　and　then　began　the　most　laborious　and　vexatious　and　painful　of　all　slow　travel。
  Once　up　on　top　of　that　lava　bed；　Gale　saw　stretching　away；　breaking　into　millions　of　crests　and　ruts；　a　vast；　red…black　field　sweeping　onward　and　upward；　with　ragged；　low　ridges　and　mounds　and　spurs　leading　higher　and　higher　to　a　great；　split　escarpment　wall；　above　which　dim　peaks　shone　hazily　blue　in　the　distance。
  He　looked　no　more　in　that　direction。　　To　keep　his　foothold；　to　save　his　horse；　cost　him　all　energy　and　attention。　　The　course　was　marked　out　for　him　in　the　tracks　of　the　other　horses。　　He　had　only　to　follow。　　But　nothing　could　have　been　more　difficult。　　The　disintegrating　surface　of　a　lava　bed　was　at　once　the　roughest；　the　hardest；　the　meanest；　the　cruelest；　the　most　deceitful　kind　of　ground　to　travel。
  It　was　rotten；　yet　it　had　corners　as　hard　and　sharp　as　pikes。　It　was　rough；　yet　as　slippery　as　ice。　　If　there　was　a　foot　of　level　surface；　that　space　would　be　one　to　break　through　under　a　horse's　hoofs。　　It　was　seamed；　lined；　cracked；　ridged；　knotted　iron。　　This　lava　bed　resembled　a　tremendously　magnified　clinker。　　It　had　been　a　running　sea　of　molten　flint；　boiling；　bubbling；　spouting；　and　it　had　burst　its　surface　into　a　million　sharp　facets　as　it　hardened。　　The　color　was　dull；　dark；　angry　red；　like　no　other　red；　inflaming　to　the　eye。　　The　millions　of　minute　crevices　were　dominated　by　deep　fissures　and　holes；　ragged　and　rough　beyond　all　comparison。
  The　fugitives　made　slow　progress。　　They　picked　a　cautious；　winding　way　to　and　fro　in　little　steps　here　and　there　along　the　many　twists　of　the　trail；　up