NOVEMBEK 17, 1911] 



SCIENCE 



663 



an opportunity is offered us through the 

 observation of the eggs of the sea-urchin. 

 If we put the fertilized eggs of the sea- 

 urchin into an abnormal salt solution, a de- 

 struction of the cell gradually takes place. 

 The destruction, as a rule, begins on the 

 surface of the protoplasm, and consists 

 very often in the formation and falling off 

 of small granules or droplets. This process 

 gradually continues from the periphery 

 towards the center until the whole egg is 

 disintegrated. For different salt solutions 

 the picture of the disintegration is a little 

 different, but sufficiently characteristic for 

 a given solution, so that if one become fa- 

 miliar with these pictures, one is able to 

 diagnose to some extent the nature of the 

 solution from the way in which the cell dis- 

 integrates. 



This process of disintegration can be ob- 

 served if the eggs are put into a pure solu- 

 tion of sodium chloride or in a mixture of 

 sodium chloride and calcium chloride, or in 

 a mixture of sodium chloride and potas- 

 sium chloride. If, however, all three salts 

 are used in the proportion in which they 

 occur in the sea-water no disintegration 

 takes place and the surface of the egg re- 

 mains perfectly smooth and normal. One 

 gains the impression as if the protoplasm 

 of the egg were held together by a continu- 

 ous surface film of a definite texture. If 

 we put the egg into an abnormal solution 

 this surface film is modified and changed, 

 and the change of the surface film is often 

 followed by a gradual process of disinte- 

 gration of the rest of the cell. 



These observations on the sea-urchin 

 egg, therefore, suggest the possibility that 

 the combination of the three salts in their 

 definite proportion and concentration has 

 the function of forming a surface film of 

 a definite structure or texture, around the 

 protoplasm of each cell, by which the proto- 



plasm is kept together, protected against 

 and separated from the surrounding media. 

 The previously mentioned observation of 

 Herbst again shows the important role of 

 calcium in this process. 



The objection might be raised that the 

 beneficial action of the three salts could 

 only be proved on marine animals or on 

 tissues of higher animals, which are said 

 to be "adapted" to a mixture of NaCl, 

 KCl and CaCla in definite proportions. 

 Experiments on fresh-water organisms, 

 for which "adaptation" to a mixture of 

 NaCl, KCl and CaCl, in these definite pro- 

 portions can not be claimed, show that this 

 objection is not valid. Ostwald worked 

 with fresh-water crustaceans which he put 

 into mixtures of various salts. It was 

 found that these animals live longer in a 

 mixture of NaCl + KCl -f CaCl^ than in a 

 solution of NaCl, or NaCl + KCl, or 

 NaCl + CaClj of the same osmotic pres- 

 sure. 



Osterhout was able to show that the spores 

 of a certain variety of Vaucheria die in a 

 pure 3/32 m. solution of NaCl in 10 to 20 

 minutes, while they live in 100 c.c. 3/82 m. 

 NaCl + 1 c.c. 3/32 CaCl^ 2 to 4 weeks, 

 and in 100 c.c. 3/32 m. NaCl + 1 c.c. 

 3/32 m. CaCl^ -J- 2.2 c.c. 3/32 m. KCl 6 to 

 8 weeks. The reaction of the solution was 

 strictly neutral and the NaCl the purest 

 obtainable. The results remained the same 

 after the NaCl had been recrystallized six 

 times. Experiments with Spirogyra gave 

 a similar result. The solutions were all 

 3/32 m. In NaCl the Spirogyra died in 

 18 hours ; in NaCl -f KCl in two days ; in 

 NaCl -f KCl + CaCl^ they lived 65 days. 

 Osterhout caused wheat grains to develop 

 in such sokitions and measured the total 

 length of the roots formed. 



