NOTEMBEK 17, 1911] 



SCIENCE 



665 



But aside from differences of this kind 

 there are other conditions which influence 

 the degree of resistance of cells to various 

 solutions. I have found that the fertilized 

 eggs of the sea-urchin will live longer in 

 abnormal salt solutions if the oxidations in 

 the egg are stopped, either by the with- 

 drawal of oxygen or the addition of KCN 

 or NaCN. Warburg and Meyerhof have 

 drawn the conclusion that in a pure NaCl 

 solution the rate of oxidations of the egg of 

 Strongylocentrotus is increased and that 

 it is this increase in the rate of oxidations 

 which kills the eggs. But this increase of 

 oxidations can not be observed in the eggs 

 of Arbacia when they are put into a pure 

 NaCl solution and, moreover, lack of 

 oxygen prolongs the life of the fertilized 

 egg just as well in solutions of NaCl + 

 CaCl^ or of NaCl -f BaCl^, for which salts 

 these authors do not claim that they can 

 raise the rate of oxidations of the egg. I 

 am inclined to believe that in the process 

 during or preceding cell division, besides 

 phenomena of streaming inside the cell, 

 changes in the surface film of the proto- 

 plasm occur, whereby this film is more 

 easily injured by the salts. If we suppress 

 the oxidations we suppress also the proc- 

 esses leading to cell division and thereby 

 retard the deleterious action of the ab- 

 normal salt solution upon the surface layer 

 of the protoplasm of the egg. 



If we now raise the question as to why 

 salts are necessary for the preservation of 

 the life of the cell we can point to a num- 

 ber of cases in which this answer seems 

 clear. Bach cell may be considered a chem- 

 ical factory, in which the work can only 

 go on in the proper way, if the diffusion 

 of substances through the cell wall is 

 restricted. This diffusion depends on the 



nature of the surface layer of the cell. 

 Overton and others assume that this layer 

 consists of a continuous membrane of fat 

 or lipoids. This assumption is not com- 

 patible with two facts, namely that water 

 diffuses very rapidly into the cell, and 

 second, that life depends upon an exchange 

 of water-soluble and not of fat-soluble 

 substances between the cells and the sur- 

 rounding liquid. The above mentioned 

 facts of the antagonism between acids and 

 salts suggest the idea that the surface film 

 of cells consists exclusively or essentially 

 of certain proteins. 



The experiments mentioned in this paper 

 indicate that the role of salts in the preser- 

 vation of life consists in the "tanning" 

 effect which they have upon the surface 

 films of the cells, whereby these films ac- 

 quire those physical qualities of durability 

 and comparative impermeability, without 

 which the cell cannot exist. 



On this assumption we can understand 

 that neutral salts should be necessary for 

 the preservation of life although they do 

 not furnish energy. 



As far as the dynamical effects of salts 

 are concerned it is not impossible that 

 some of them belong also to the type of those 

 mentioned in this paper. The fact that 

 the addition of calcium to an NaCl solu- 

 tion prevents the twitchings of the muscle, 

 which occur in the pure NaCl solution, 

 suggests the possibility that the CaClj 

 merely prevents or retards the diffusion of 

 NaCl through the sareolemma. But other 

 effects of salts, e. g., the apparent depend- 

 ence of contractility of the muscle upon 

 the presence of NaCl ; or the role of PO4 in 

 the nucleus, do not find their explanation 

 in the facts discussed in this paper. 



Jacques Loeb 



Rockefeller Institute 

 FOE Medical Research 



