660 



SCIENCE 



[N. S. Vol. XXXIV. No. 881 



This, however, is probably not the direct 

 cause of the death, but I am inclined to 

 assume that the fish die from suffocation 

 caused by a similar action of the acid upon 

 the gills. 



The action of the acid upon the epidermis 

 of the body as well as upon the gills is pre- 

 vented through the addition of neutral 

 salts. 



It is well known that the action of acids 

 upon proteins can be inhibited by neutral 

 salts. Thus the internal friction of certain 

 protein solutions is increased by acids while 

 the addition of neutral salts inhibits this 

 effect (Pauli). The swelling of gelatine 

 caused by acid is inhibited by salts 

 (Procter) . 



It is possible that in the experiments 

 with acid the fish is killed in the following 

 way. The acid causes certain proteins in 

 the surface layer of the epithelial cells of 

 the gills and of the skin to swell, whereby 

 this surface layer becomes more permeable 

 for the acid. The acid can now diffuse into 

 the epithelial cells and act on the proto- 

 plasm, whereby the cells are killed. If 

 salts are present in the right concentra- 

 tion, the combined action of acid and salt 

 causes a dehydration of the surface film of 

 these cells, as it does in the experiments on 

 gelatine or as in the eases of tanning of 

 hides by the combined action of acids and 

 salt solutions. This combined dehydrating 

 or "tanning" action of acid and salts on 

 the surface of the epithelial cells of the 

 gills diminishes the permeability of this 

 layer for the acids and prevents them from 

 diffusing into the cells and thus destroying 

 the protoplasm. In this way the giUs are 

 kept intact and the life of the fish is saved. 

 As long as the amount of acid is small 

 the amount absorbed is not essentially 

 diminished by the presence of salts; but 

 while in the presence of salts the acid is 

 consumed in the tanning action of the sur- 

 face layer of the cells, or is absorbed in 



this layer ; if no salt is present part of the 

 acid diffuses into the epithelial cells and 

 kills the latter. 



VII 



We have thus far considered the cases of 

 antagonism between two electrolytes only. 

 The case of the antagonism between three 

 electrolytes is a little more complicated. 



We choose as an example the antagonism 

 between NaCl, KCl and CaClg — the antag- 

 onism which is most important in life phe- 

 nomena. If the mechanism of the antag- 

 onism between NaCl, on the one hand, and 

 KCl and CaCl,, on the other, is of the same 

 nature as that between NaCl and ZnS04 in 

 the case of the eggs of Fundulus, it must 

 be possible to show that not only is NaCl 

 toxic if it is alone in solution, and that it is 

 rendered harmless by the two other salts, 

 but that the reverse is true also. This can 

 be proved in the case of KCl. To demon- 

 strate it, we have again to experiment on 

 organisms which are, in wide limits, inde- 

 pendent of the osmotic pressure of the sur- 

 rounding solution since the concentration 

 of the KCl in sea-water is very low. The 

 experiments were carried out by Mr. Was- 

 teneys and myself on Fundulus. The 

 method consisted in putting six fish, after 

 washing them twice with distilled water, 

 into 500 c.c. of the 'solution. It was ascer- 

 tained from day to day how many fish 

 survived. 



When the fish were put into pure solu- 

 tions of KCl of the concentration in which 

 this salt is contained in the sea-water 

 (2.2 c.c. m./2 KCl in 100 c.c. of the solu- 

 tion) they died mostly in less than two 

 days. This is not due to the low concentra- 

 tion of the KCl solution, which is only 1/50 

 of that of the sea-water, since the fish can 

 live indefinitely in a pure NaCl solution of 

 the same concentration as that in which the 

 KCl exists in the sea- water. 



If we add to the toxic quantities of KCl 

 increasing quantities of NaCl, we find that 



