1904 | KEARNEY: PLANTS OF SEA BEACHES AND DUNES 431 
made to a depth of 6%, the first 3°™ giving an electrical resist- 
ance indicating about 0.006 per cent. of water-soluble salts, 
the second about 0.004 per cent. The results here were there- 
fore closely comparable with those of the two borings made in 
December on the outer beach in Virginia.” 
The second boring on the Massachusetts beach was made to 
a depth of only 3%", on the outer limit of vegetation, at a point 
where a small tidal inlet crosses the beach. The coarse sand 
here contained considerable partially decayed vegetable matter 
(chiefly Zostera) and was nearly saturated with water. The 
vegetation consisted of numerous vigorous plants of Cakile 
americana, and a few plants each of Sadsola Kali, Ammodenia 
peploides, Atriplex arenaria, Ammophila arenaria, and Xanthium sp. 
The electrical resistance of the water-saturated sand here indicated 
the presence of about 0.03 per cent. of salts—about six times as 
much as was found in the first 3°™ of the preceding boring. 
This difference was doubtless due to the second boring having 
been taken at a point nearer the level of flood tide and quite 
close to the bank of a tidal inlet. 
All the beach and dune soils examined along the Atlantic 
coast of the United States contained a considerable amount of 
water at a slight depth below the surface, which is indeed a 
well-known peculiarity of such soils. The data just given make 
it sufficiently evident that this water does not come from the 
sea, unless we can assume that sea-water, moving through but a 
few meters of sand, will give up nearly all the soluble salts it 
normally contains.* This assumption is @ priori unlikely, and 
** The remarkably small amounts of salts present in the dune and beach soils just 
extensively over or through the soil. ‘The necessity for feeding over the largest pos- 
ible area of the sterile soil may cooperate with the necessity for the firmest possible 
foothold in the shifting, unstable sand in producing this habit of growth. 
aA number of samples of ocean water were taken on the Challenger 
Expedition. ge these a sample of surface water from near the latitude of Woods 
Hole (lat. 40°17' N., long. 66°48’ W. sccens open 3-287 parts per 100 of total solids, as 
estimated by Diener method from the chlorin content; while a sample of bottom 
