OF VITAL PHENOMENA 97 



It is well known that plants concentrate some of the salts of 

 the water that bathes their roots. This is not entirely due to 

 the evaporation of the water from the leaves, since the same 

 is true of water plants. The ash of the kelp, Nereocystis, of the 

 Pacific coast may contain 67.5 per cent KC1. The KC1 in the kelp 

 juice is 0.38 n and in sea water 0.01 n. The ash of Iridaea 

 edulis contains 23.42 per cent K=45 per cent KC1. According 

 ot Stoklasa, however, the ash of Azobacter is almost pure K salts 

 (laragely phosphates). The mechanism by which the potassium 

 is selectively absorbed is unknown. According to Meigs and 

 Atwood (1916) if muscle is placed in pure KC1 solution it ab- 

 sorbs the KC1 faster than the water. 



It is certainly true that some neutral salts penetrate some plant 

 cells with exceeding slowness. It was observed by chemical 

 analysis that several grams of yeast absorbed not more than 

 two milligrams of MgCl 2 from a molecular solution in five hours 

 (McClendon, 1912 d). Furthermore, Paine (1912 a) used chem- 

 ical methods and found that yeast absorbs very little if any from 

 more dilute solutions of neutral mineral salts, whereas it ab- 

 sorbs alcohol rapidly. The partition of ethyl alcohol between 

 yeast and water is 0.85 to 1. 



The permeability to injurious substances will be considered 

 under changes in permeability. 



The permeability of animal cells is very similar to that of 

 plants. Overton (1902 a) studied the permeability of frog's 

 muscle, concluding that it is essentially the same as that of plants. 

 The relation of muscle to salts is of special interest. Muscle 

 and blood cells store potassium and it is supposed that if they 

 are permeable to salts the potassium will come out and sodium 

 go in, until equilibrium with the blood plasma is reached. Over- 

 ton claims that neutral salts that do not injure muscle do not 

 penetrate it to any extent. When placed in an isotonic solution 

 of a non-toxic potassium salt, such as the tartrate, the weight 

 of the muscle did not change in fifty hours, but when placed in 

 a toxic isotonic solution, such as KC1, the muscle soon began to 

 swell and died, so that it did not regain its original weight if 

 returned to Ringer's solution. Meigs and Atwood (1916) and 

 Siebeck (1913) claim that muscle is permeable to K, but Urano 

 (1908 c) and Fahr (1909) were unable to wash out the potas- 

 sium from muscle with isotonic sugar solution. 



