350 



was seen to be discoloured by the moisture absorbed, and the 

 plants were copiously sprinkled with dew. At 7 a.m. on January 30 

 the water was dripping from the branches of the Tamarisks in the 

 Khan valley at Haikamchab. That so regular and abundant a 

 deposit of moisture should not be able to support a greater number 

 of shallow-rooted plants than are found on the Namib seems at 

 first remarkable. The explanation is no doubt to be found, in 

 part at least, in the presence of a large proportion of soluble salts 

 in the surface layers of the soil. Further, the temperature at the 

 surface during the daytime is probably on most days sufficiently 

 high to be injurious to germinating seeds. 



Soil Temperatures.— The following temperatures of the upper 

 half-inch of the sandy soil (in one case of a rock-surface) were 

 recorded at Haikamchab. The observations, though not made at 

 the same spot, were all taken at approximately the same elevation, 

 and at points not more than two miles apart. The records are not 

 all for the same day— a fact which, owing to the marked uniformity 

 ol the climatic conditions, is probably not of great importance : 



Jan. 31. 6.0 a.m. ... 22-0° C. 



Jan. 30. 9.20 a.m. ... 44-0° C.' (rock- surface) 



Jan. 29. 10.20 a.m. ... 46-0° C. 



Jan. 30. 10.20 a.m. ... 48*25° C 



Jan. 31. 12.30 p.m. ... 52'5° C*. 



Jan. 29. 2.45 p.m. ... 54-0° C. 



Jan. 30. 4.50 p.m. ... 440° C 



Jan. 30. 9.0 p.m. ... 29'0° G. 



can^n'rlnLT 1 " 86 ' "?" k ??T l that seeds in the «**«« condition 

 ir m ,v ho *T Pe ; atUre ^ hlgher than M ° C ' without bein S injured. 



wiWn w n ' ?u Worth re ™ rdin Z that Wdwitnehia seeds which 



daib Zl J T the g :° Und f0r Six montbs objected to such a 

 hi llhedTnVl- r atme , f is indicated b y the above figures, 

 wi hi nlZfntul 1 ? 1 desiccated again by day, germinated 

 cTref "l J^ g nder laborator y conditions. In spite of most 

 showed an vt;fr^ Were ^ Under natural conditions which 

 tion I ordp?/n ? d + S,gU ° f even the commencement of germina- 

 te ^dam mlxirn^f a 8UCC ! SSf Ul S ermin "tion on a plateau subject 

 seed rnusf eTtW l, Pe /n UI * e GVen SOme Agrees below 54° C., a 

 PositioTor iS P^h. Ve faUen in an ^eptionally favourable 



Sn has comwnr/ 1 gr0W Very rapidly when once germi - 

 reg ons must W. T df ™ i 3gam the P r °toplasm of its growing 



^L^^ qmred an unusual power of resistance to 



^n^iZZ^Z Namfb P"SS "* '* aVai,able *" "3 

 at Wei witseh in lSi * i ? b# Obser vations were commenced 



the beaTnn-n- of S °/ f* yeap ' No measurable rain fell from 



^^ST^^^S^ November but 12 ' 5 ram - were 



on^se^Hfe ^? in^^ 7 -^"** field for observations 

 great daily ran -e of ? * 1 " llmination » the hi S h maximum and 

 during the St ^^r^ 1,6 ' the c °Pio"B deposit of moisture 

 l^night^and the great variety and peculiarity of the 



See also Appendix I 



