664 



SCIENCE 



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



Total Length of . 3 

 Nature of the Solution Boots after 40 Days 



H2O 740 mm. 



100 C.C. 3/25 NaCl 59 mm. 



100 c.c. 3/25 NaCl+2.0 3/25 CaCI, 254 mm. 



100 e.e. 3/25 NaCl+2.0 3/25 CaClj 



+ 2.2 3/25 m. KCl 324 mm. 



These cases, to whidi many other similar 

 observations might be added, prove that 

 the life-preserving efPect of the combina- 

 tion of NaCl + KCl + CaClj in definite 

 proportions is not due to the fact that or- 

 ganisms are "adapted" to this mixture but 

 to a specific protective effect of the combi- 

 nation of the three salts upon the cells. 



It seems, therefore, to be a general fact 

 that wherever tissues or animals require a 

 medium of a comparatively high osmotic 

 pressure — like our tissues — their life lasts 

 much longer in a mixture of NaCl + KCl + 

 CaClg in the proportion in which these 

 salts exist in the blood and in the ocean, 

 than in any other osmotic solution, even a 

 pure solution of NaCl. But the reader has 

 noticed that there are considerable differ- 

 ences in the resistance of various organ- 

 isms to abnormal solutions. While marine 

 Gammarus die in half an hour in an iso- 

 tonic solution of NaCl or cane sugar, red 

 blood corpuscles or even the muscle of a 

 frog can be kept for a day or longer in 

 such a solution (of course even the muscle 

 of a frog lives longer if the NaCl solution 

 contains in addition KCl or CaClj). "What 

 causes this difference? 



Six years ago I found that the unfertil- 

 ized eggs of the sea-urchin {Strongylocen- 

 trotus purpuratus) can keep alive and re- 

 main apparently intact in a pure neutral 

 solution of CaCla or of NaCl for several 

 days at a temperature of 15°, while the 

 fertilized eggs of the same female are 

 killed in a pure neutral solution of CaClj 



in a few hours. The same difference is 

 found for other salts also. What causes 

 this difference? Several authors, Lillie, 

 McClendon and Lyon, have suggested that 

 it is due to the fact that the fertilized egg 

 is more permeable to salts than the unfer- 

 tilized egg. But the recent experiments by 

 Warburg, which were confirmed and ampli- 

 fied by Harvey make it doubtful whether 

 the salts which are not soluble in fats can 

 enter the fertilized egg at all. I believe 

 that the explanation of the difference is 

 much more simple. The unfertilized egg is 

 surrounded by a cortical layer and this 

 layer is destroyed or modified in the proc- 

 ess of fertilization. One result of this 

 modification is the formation of the fertili- 

 zation membrane, for which I have been 

 able to show that it is readily permeable 

 for salts. As long as the cortical layer of 

 the unfertilized egg is intact, it prevents 

 the surrounding salt solution from coming 

 in contact with the protoplasm or at least 

 it retards this process. If, however, the 

 cortical layer is destroyed by fertilization 

 the surrounding salt solution comes directly 

 in contact with the protoplasm and if the 

 solution is abnormal it can cause the dis- 

 integration of the surface layer of the 

 protoplasm. 



I am inclined to believe that differences 

 in the resisting power of various cells or 

 organisms to abnormal salt solutions are 

 primarily due to differences in the consti- 

 tution of the protective envelopes of the 

 animals or the cells. Microorganisms 

 which can live in strong organic acids or 

 salt solutions of a high concentration prob- 

 ably possess a surface layer which shuts off 

 their protoplasm from contact with the so- 

 lution. For the protoplasm of muscle the 

 rather tough sareolemma forms not an 

 absolute but nevertheless an effective wall 

 against the surrounding solution. 



