434 BOTANICAL GAZETTE [JUNE 
We have then a much higher content of soluble salts in the 
beach sands of the coast of southern California than in cor- 
responding situations on the Atlantic coast of the United States. 
The fact that the sand was much drier at Long Beach than in 
the localities examined in Massachusetts and Virginia gives us 
the clue for a probable explanation of this difference. In all 
likelihood, climatic differences between the two regions, especially 
as regards quantity and distribution of the rainfall, account for 
this marked difference in the salt content of the soils. Where 
the rainfall is slight, either throughout the year or at some one 
season, the concentration of the soil solution must correspond- 
ingly increase, for evaporation from the surface is constantly 
going forward. The same climatic conditions which cause the 
formation of extensive tracts of saline soil in the interior of con- 
tinents will, caeteris paribus, bring about a similar result along 
the coast. The mean annual rainfall at Los Angeles is 39.3°™, 
and normally only 0.5°™ falls in that region between June 1 and 
September 30. At the time the results just described were 
obtained (September 29, 1903), only 1.12°™ of rain had fallen 
during the previous four months. 
At Norfolk, on the other hand, the mean annual rainfall is 
130.2°™, and during the four months from June 1 to September 
30, it is 52.05°™. Inthe two months preceding the date on which 
the soil samples above described were taken, 7. ¢., October and 
November 1903, 20.5°™ of rain fell. Furthermore, in the season 
of the year when the examination was made near Norfolk (De- 
cember 2), evaporation must be considerably reduced and the 
tendency towards a concentration of salts near the surface of 
the soil due to this cause, in conjunction with the capillary rise 
of water in the soil, must be considerably less than during the 
summer. However, the results obtained in midsummer on the 
coast of Massachusetts, where conditions as to rainfall are much 
like those on the Virginia coast, go to show that the concentra- 
last components to be leached out of the soil by subsequent rainfall. In salt marsh 
soils, on the other hand, the daily ebb and flow of the tide prevents any marked accu- 
mulation by evaporation of such calcium salts as are deposited. But the Sepsis 
inland cannot be ignored, since California soils are often very rich in lime. 
