GENERAL PHYSICAL CONSTITUTION OF LIVING MATTER 51 



nism between the precipitating effects of salts of univalent and bivalent 

 metals, which Linder and Picton had already found. If arsenic sulphide 

 is precipitated with a mixture of two salts with a univalent cation, or 

 of two salts with a bivalent cation, the effects of the two salts are added 

 to each other. If a mixture of a salt with a univalent cation and a salt 

 with a bivalent cation is used, however, for the precipitation, the result 

 is an inhibition instead of a summation of the effects. Hober and 

 Gordon have repeated and confirmed this observation. In addition, they 

 have found that, just as in my own experiments, the valency of the 

 anion plays no r6le. I am not able to state whether this explains the 

 observations made on Fundulus. 



It is rather remarkable that many authors have found distilled water 

 to be poisonous for fresh-water animals. Locke showed that some 

 authors had been deceived by the fact that their distilled water contained 

 traces of copper salts, owing to the fact that the water had been distilled 

 in copper vessels. But BuUot* found that for fresh-water Gammarus 

 distilled water is toxic even if distilled with all necessary precautions in 

 Jena glass or quartz or platinum vessels, and if care is taken that it is 

 free from ammonia. He found that if a trace of NaCl is added to the 

 distilled water (so that the concentration of the latter was 0.00008 N) 

 fresh-water Gammarus could live indefinitely in the distilled water. 

 The presence of a trace of NaCl in the distilled water possibly preserves 

 the membrane better, or maintains better the secretory activity of the 

 cells so that the animal can be freed from the excess of water which 

 diffuses into it. 



Dr. Wolfgang Ostwaldf investigated the duration of life of the same 

 fresh-water Gammarus in solutions of higher concentration. He 

 found that these animals live longer in a mixture of one hundred mole- 

 cules NaCl, two molecules KCl, and two molecules CaCL,, than in a 

 pure sugar or NaCl solution of the same concentration. This is in 

 harmony with the assumption that the absorption as well as the secretive 

 action of the cells requires the presence of Na, Ca, and K in definite 

 proportions, as we shall see more fully later. 



In connection with these experiments I made an observation which 

 possibly may become of some use in the study of the phenomena of adap- 

 tation. When marine Gammarus is put into sea water, which has been 

 diluted with various quantities of distilled water, one notices that, with 

 increasing dilution of the sea water, the duration of hfe of the Gammarus 

 at first diminishes but Uttle ; that, however, at a certain degree of dilu- 

 tion (about ten times that of the normal sea water) the duration of life 



* BuUot, University of California Publications, Physiology, Vol. I, p. 199, 1904. 

 t W. Ostwald, Pfiuger's Archiv, Vol. 106, p. 568, 1905. 



