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GCONEENES: 
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ememeanoratory Location Trip ... <. - 6 <- 2. dete eee ee ie ee ee eee ber 2 
Earlier Investigations and Development of Department of Botanical Research.. 3 
Desert Regions of North America........--- see ec se eee see rte e rene aneerets 
eae from the Humid Regions to the Chihuahua Desert, in Western 
eee cee PRLS oy 8 idee A. ig sa. eens » AR ones "y: aj Vet ee epee Mana Tat ae Bm ie 
ie Sand-dines of Chihttahtia ...fs.c. se erent ee cee eeu eenananen es ae 
SET SR eOAT SLIT Pe ne oie aioe «painless = Seely oe era etd eee aoe aaa RST once II 
Nogales and the International Boundary ReQiOT ice sntsline ai pa mre keer 18 
eet ec ake xii ns Sa. 9) © WM le mm 4 nt my ean aaah eapagahie + asa e 19 
“OV ae lara al ee Af ne Ii aa 21 
Reha S48 ck yo mca cher ahs Shak cies dhs W's "Chie Tas ns col 0 feu os tay meme A ap ote ce oo gg rae te 2I 
eo eee Ener re striae re cnt wy eet eee ee 26 
ree cancel ities 2 etek a7 a os a ss eel ie ole hale REP Wisin = x fe erate He 27 
Sage-brush Deserts of Nevada and ESC cers ie coe sw Sees Ps) ancvete sie alghsi are 28 
Tie Misnavc LGSOrbs oo ua iw oe es eins e tayene meen Unie eA Aw mi sae Neste se 30 
DP alleys oe ee ite go ine hm ad open mpgs me aa a dels Bae es aI 
Grand Canyon of the Colorado River. ...... eee eee e cree reece entrees ac 
The Delta of the Colorado River... .... 2s cece ee eee tere eee e reece tees 33 
Mite Sonoran DeSertsy. ccc c ce wee nee cee eee ee erence eae ar eens 34 
The Colorado Desert........-+-+++ +000: SRN eaaeLe dat sake wa seitre tA mean e 35 
The Cucopa Mountains and the Pattie Basin.......----+++++++s+0-- 40 
_ The San Felipe Desert in Baja California.......--- +. ++ee ese ee reece 42 
Tucson, the Site of the Desert Laboratory ........e see e reer tree et eter cece: 44 
Geological Sketch of the Region of Tucson, PTZ i een ia eg ae stg 45 
Pierioeraphy and Geology 5 © 66. be iene ee ee ee nee en ee tee ene ene 45 
Piemanta Catalina Ranges i... 6. sce eee ve eee aie ee eee eases tees 46 
MUR rs ic as hs aial's wow ciece toain wid to wis oe, trance igi nRia ee sie AK wpe Owe 2 WF os 47 
MENS acisty KANIOG, (6.0 ete te pee a VE Re Re Ry See os 48 
The Valley of the San Pedro River. .... 0... see ect er ete tere creer ereress 49 
Me eariia Rita RANGE. 2 faye nce ees le cn ss Hee tone ce a Helsing vinelain ees 50 
ee Fy Vit G ole ss hg ered co we Ss ow wie inlets BS Wie tee Mergians Sees ees 52 
The Sierritas and the Tucson Mountains. ........- eee secrete rere renee 53 
ie ea eat py aren nla a San Fea ale me id ogame nem arene Rey ©) ©. 9.5. #8 > 54 
Me Mountain SIOPES.... 0.2650 e ee ew cee rete nse s Cee we cess anes e rebels 56 
Oe est CID ES cn cacain en en whe Sho ia e ee S a Spee ie Ree ole en ote sie A 58 
ERED GENG ODES oi. ome nee poise oe me mr iinet ete ain gees Sak Sine 60 
Former Lacustrine Conditions........... ese e eee rece eect ence eee re cnee 61 
Be orale at Chie: REQIONL Kae sos are nw a oe sic win alee ences ey nie ne oie ee en mH ae 61 
PUNE D2 cia Cage SS eae racic ICR SE Ia 62 
Mee re re tg ie eo 2 winlvla) wai vie wie qiecsh ole’ dee whee ae: 4\ 40s eisir de wees 63 
ee et Re eco ie vaekn sheer ig <.nieile nhc 9) ato aah '8 THN ke win! a's sie ganiaiane 0am 64 
See 7S a ne ag eee ae er I a RRM ec ai 66 
Extinction of the Great Mammals ........- sees cece rene tee ener re recere 66 
Submergence and Elevation .......-s2esesecercresssseecereserererens 67 
Aspect of the Vegetation about Tucson .......e essere rere reece esses ese cs 68 
Me Parentiials. 4.0 oc access ccc cease ene dene ce eels es eee so 68 
ees eiig tla 20 ie & Wield wcer'a «Hiv lai win w of 04 sa. e % wcokehiecdlo hin aliel sf idinee: mage ee Ap 69 
Spinose and Succulent Forms of the Dry Foresummer......-+.+-+++-+++-- aI 
Plants in the Humid Midsummer ......... cece cere eee reer cere ree erees 45 
reerets PST etitt eS ee cece die 0D oie! ojo tee che iti a ays Wintel ee epee winr= eels ele 75 
a rarnOs ATINUAIS. «2 pen eck Korie a oe ee ea wale om Sie weit ee le nis Hw sek me a inltie ig es 76 
The Dry After-summer.......5 6-222 eee e dee rea eee ee eet were ens 76 
Temperatures of Plants in the Desert......-+-+se sees eeere rer ceer ere eerers 77 
The Water Relations of Desert Plants.......-. see ee crete eee e rere reer ecans 83 
The Soil Relations of Desert Plants.......-csesccerserecereses sence ccrcrers 87 
Conditions Contributory to Deserts......-. see c eee c eee e erence teeter er eeeee gt 
SSS BEd oer erreorogrmror. cs 1 0c te ceck ton oe Cem manr ra 92 
Meteorological Table ........ceeseeees esc c creer eter enccceees 93°94 
EE ee ae reer eee ocr ee ea 97 
ey han Sain eines nie ow Dip Fine oe nm oe en wise Rigs olathe as 100 
Formation and Extent of Deserts .........s cece cece cere reece cence ace cens 102 
