ELECTROLYTES IN LIVING MATTER g^ 



n 



Similar conditions exist for the development of the eggs of a 



sea urchin, Arbacia. I found that in neutral solutions of NaCl, KCl, 

 CaClj, MgCl^, MgS04, the eggs of Arbacia can reach the pluteus stage, 

 but that no normal skeletons are formed. If, however, NaHCOj is 

 added, normal skeletons are formed. Similar results were previously 

 obtained by Herbst, and in this case also the NaHCOj serves for the 

 neutralization of an acid. Experiments in Strongylocentrotus purpura- 

 ius were still more surprising in this respect.* When these eggs were 

 put immediately after fertilization into a van't Hoff solution (loo NaCl, 

 2 KCl, 2 CaClj, 7.8 MgClj, 3.8 MgSOJ, only few eggs went beyond the 

 two-cell stage, and only very few reached the pluteus stage. If, however, 

 to 100 c.c. of such a solution 0.5 to i.o c.c. | m NaHC03 were added, 

 almost all the eggs went into the pluteus stage. In such a solution the 

 development also occurred just as fast as in normal sea water. 



The addition of o.i c.c. f w NajC03 solution caused also some eggs 

 to reach the pluteus stage. These plutei, however, did not live as long 



ft 



as when the bicarbonate was added. When 0.2 to 0.4 — NaHO was 



10 



added to 100 c.c. of the van't Hoff solution, the majority developed, but 



no skeletons were formed. We must, however, take into consideration 



the fact that in such solutions, as I found, NaHO is neutralized in a few 



hours or in less than a day by the CO^ of the air and the CO^ formed 



by the eggs, while the formation of a skeleton occurs only after from 



forty-eight to seventy-two hours. The addition of 0.8 c.c. of a ^ 

 Na2HP04 solution acted similarly to the addition of NaHO. 



I think these examples may suffice to show the importance of a 

 regulator which is capable of keeping the solution in which marine 

 animals live neutral. The same is true for the liquids in which tissues 

 live ; this point was investigated by Rogers in experiments on the heart 

 of the crab. Here, also, the addition of bicarbonate made a great differ- 

 ence. This is also, as I beheve, the explanation of the fact that Ringer's 

 solution is improved through the addition of a trace of NaHCOj . Gaule f 

 was the firsf to point out the necessity of neutralizing the acid formed in 

 the heart if we wish to make it beat in an artificial solution. In fresh- 

 water animals, Wolfgang Ostwald made the interesting observation that, 

 if Gammarus be put into a salt solution of a comparatively high osmotic 

 pressure, life could be prolonged considerably by adding NaHCOj 

 to the solution. He was able to show that without the addition of the 



* Loeb, P/luger's Archiv, Vol. 103, p. 503, 1904. 

 t Gaule, Du Bois-Reymond's Archiv, p. 291, 1878. 



