246 D. T. IfacDougal—The Salton Sea. 



The other element to be considered would be the species 

 native to the valley of the Colorado River. The entrance 

 from this region would be principally by flotation. The 

 number of species included would be too large to be discussed 

 in detail. Only those with seeds which would be uninjured by 

 long immersion would constitute potentialities in invasion 

 from this source. The census of the invasions from 1907 to 

 1912 inclusive includes 60 species. 



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 farther. 



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 might be picked up by the water and 

 carried the entire distance, or the seedlings might endure 

 aquatic conditions for extended periods. 



The heavy winds from the southeast, southwest and north- 

 west would lift and carry a large variety of seeds (such as 

 those of Baccharis and Pluched) long distances. Some 

 might fall to the ground directly on the bared strand exactly 

 at a time when the germination 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 wind. 



Traveling animals, especially birds, might bring seeds 

 attached to their feathers or imbedded in mad clinging to 

 their feet. In the present instances the principal birds were 

 the pelican, cormorant, and various species of ducks. The 



