1915 Brown; Experiments tvith Algae 33 



water is actually harmful. It was expected that the plants would grow 

 in fresh water from their preference for seepages of fresh water on 

 the ocean beach. It was, however, unexpected that they would grow larger 

 in fresh water, since they are not normally found there. Livingston's 

 work^ on Stigeoclonium indicates that strong osmotic solutions tend to 

 keep cells from elongating, i. e., increasing in size. Hence those in the 

 saltier water were likely smaller because the osmotic pressure retarded 

 the enlargement of the cells. However, no expriments were made looL 

 ing toward a proof of this. 



That the general effect of strong osmotic solutions is to retard 

 growth is known, and the literature has been summed up by Livingston.* 

 But one would naturally expect that a marine algae would grow best in 

 the sea. 



The results also suggest that the smaller forms of Enteromorpha 

 intestinalis commonly found in salt marshes and in salt lagoons are due 

 to stronger osmotic solutions formed by evaporation. If this proves true 

 it would shed a great light on the puzzling varieties and forms of Entero- 

 morpha intestinalis. 



Tests were made with other algae to see how they can endure fresh- 

 water solutions. Some Fucus evanescens, Gloiopeltis furcata, Prionitis 

 lyallii and Rhodomela larix were placed in a tub of 90 per cent sea 

 water. The per cent of sea water was reduced by 10 every three days. 

 When the solution was about 40 per cent the Gloiopeltis succumbed. The 

 other plants had a whitish coating and looked sickly, but were rather 

 tough in texture and withstood unfavorable conditions better than Gloio- 

 peltis. Evidently they all could not stand the change. 



A tub of salt water was placed under a building where a small tap 

 of fresh water could run into it. Into this were placed some Nereocystis 

 luetkeana, Desmarestia aculeata, Cymathaere triplicata and Laminaria 

 saccharina. The tub was filled with salt water so that the plants would 

 be spared the shock of a sudden change to fresh water. On the second 

 day the tub was emptied so that the plants were then in a tub of run- 

 ning fresh water. On the third day the Nereocystis and Desmarestia 

 looked sickly. On the fifth day the fronds of Nereocystis had fallen off 

 and the whole plant was soft, Desmarestia had changed color, and Cyma- 

 thaere and Laminaria had begun to soften. Either these plants cannot 

 resist the bacteria of decay present in fresh water or they need the salts 

 in solution. These also therefore could not stand the fresh water. 



Some Fucus evanescens, Prioniti lyallii, Rhodomela larir and En- 

 teromorpha intestinalis were placed in pools in a stream of fresh water. 



sPhysiological Properties of Bog Water. Bot. Gaz., 39: 348-355. 1915. 

 4The Role of Diffusion and Osmotic Pressure in Plants. Chicago, 1903. 



