MOVEMENTS OF VEGETATION IN THE SALTON SINK. 143 



ments found in the Salton Lake water and it does not seem profitable therefore to reduce 

 the chemical results to terms of normal concentration. Sodium was present in the water 

 of the lake to the extent of 112 parts in 100,000 in 1907, and calcium to less than 10 parts, 

 the calcium therefore being but one-eleventh of the amount of the sodium. The ratio had 

 changed but little by June 1908, but by June 1909 the sodium was as 13 parts to 1 of cal- 

 cium, and the period immediately preceding may be taken as being the time when the 

 sulphur bacteria began to multiply and take on an increased aggregate activity, resulting 

 in the reduction of the sulphates and the deposition of calcium carbonate. Although the 

 water coming into the lake from various sources was charged with calcium in small pro- 

 portion, yet in 1910 the ratio of sodium to calcium had increased to 14 to 1, in 1911 to 14.5 

 to 1, in 1912 to 14.62 to 1, and in 1913, 16.4 to 1. 



Many physical agencies would operate to carry seeds toward the sterilized beaches, 

 and it will be profitable to consider some of the possibilities upon which only inferential 

 evidence may be offered. 



The Colorado River at the time that it poured the greatest volume of water into the 

 lake was in a state of flood and had spread out over the lowlands along its course, lifting 

 millions of seeds from their resting-place on the ground; these would be carried toward 

 the lake. Some kinds, however, because of their specific gravity, would sink, and these 

 would have very little chance of reaching the strands of the lake, as they would soon be 

 covered with silt. Others which might float at first would soon become softened and by 

 the imbibition of water would swell as if for germination, with the result that these also 

 would be destroyed before they passed through the long overflow channel leading from the 

 main channel into the Salton Sink, and some might actually proceed to germination, the 

 plantlets being carried still further, as is suggested by the results on pages 144-153. 



Some of the heavy seeds might adhere to trunks of trees and other floating objects 

 and be carried with them to a final resting-place on the strands. In all cases, however, 

 seeds of any kind would be subjected to the action of the saline water as soon as they 

 were thrown into the waters of the lake. Seeds with indurated outer coats, such as some 

 of the species examined in the flotation tests described on page 164, might be picked up 

 by the water and carried the entire distance, or the seedlings might endure aquatic condi- 

 tions for extended periods (see page 150) . 



The heavy winds from the southeast, southwest, and northwest would lift and carry 

 a large variety of seeds (such as those of Baccharis and Pluchea) long distances. Some 

 might fall to the ground directly on the bared strand exactly at a time when the germina- 

 tion conditions were most favorable. Much greater numbers would tend to fall on the 

 surface of the stream and of the lake itself. Once in the water, their further transportation 

 would depend upon wave-action, which would be produced by the wind. 



Traveling animals, especially birds, might bring seeds attached to their feathers or 

 imbedded in mud clinging to their feet. In the present instances the principal birds were 

 the pelican, cormorant, and various species of ducks. The first two feed upon fish and 

 habitually alight either on rocks or branches of trees rising above the level of the water, 

 or upon the arid rocky soil about their nests, as noted on the various islands. In one case 

 the seeds would be dropped in the water and their origin would escape analysis, while in 

 the second instance the soil would be too dry to induce germination, which if it did take 

 place would end disastrously, since the surface about the nesting-grounds was trampled 

 and worn so that green plants had but little chance of survival. Pelicans also alight and 

 stand in ranks along muddy shores, and might in this manner deposit seeds in rows or lines. 



The lake occupied the bottom of the bowl of the Cahuilla Basin and drainage channels 

 from all of the converging slopes led toward it. In none of these, however, were there constant 



