128 Papers from the Marine Biological Laboratory at Tortugas. 



the fact that it can be suppressed is of importance in my technique, since 

 the presence of the membrane might be considered as a source of error. 



The increased conductivity of the eggs indicates increased permeabiUty 

 to electrically charged particles, since electrons can not pass in the free state 

 through solutions without very soon attaching themselves to atoms. The 

 particles concerned must be ions, since colloidal particles move slowly and 

 carry little electricity per unit mass, and could hardly cause the great in- 

 crease in conductivity observed. 



This increase in permeability was confirmed by plasmolytic experiments 

 on the eggs of Arbacia at Woods Hole. 



What ions are concerned in the increase in permeability has not been 

 determined. Experiments which I made on the Fu?ididus egg are sugges- 

 tive.^ Funduliis eggs (which normally develop in sea-water), when develop- 

 ing in distilled water, do not give up chlorides to the water. If placed in 

 sulphates or nitrates of sea-water metals, they still do not give up chlorides. 

 If placed in distilled water they do not give up magnesium (or calcium). 

 But if placed in sodium salts they lose magnesium (and probably calcium 

 and potassium), and chlorine, because the pure sodium increases the 

 permeability. 



A critical review of the literature on permeability is given in a previous 

 paper^ but I shall here refer to some of it briefly. In the summer of 1910 

 R. Lillie, Lyon and Shackell, E. N. Harvey, and the author, all working on 

 the sea-urchin's egg, had come to the conclusion that its permeability 

 increased on fertilization. Very shortly there appeared a paper by Loeb^ in 

 which he made this statement: 



In former papers, especially in a book published a year ago, I pointed out that the 

 process of membrane formation, or a certain alteration of the surface of the egg, is the 

 essential cause of the development of the egg; and I pointed out, also, that this alteration 

 of the surface might increase the permeability of the egg, especially for hydroxyl ions. 



1 have found one such paper/ but it was directed against the view that 

 the cell is impermeable to electrolytes, and gave evidence to show that the 

 egg is more permeable to salts than to sugar. In the book referred to^ 

 Chapter xiii deals largely with permeability and ends with the following 

 conclusion (on page 118): 



Wir kommen also zu dem Schluss, dass die Hydroxyloinen des Seewassers auch in das 

 unbefruchtete Ei diffundieren, und dass die Membranbildung des Oxydationen im Ei nicht 

 dadurch steigert, dass sie die Durchgangigkeit desselben fiir Hydroxylionen erhoht, sondern 

 dass sie die fiir die Entwicklung notigen Oxidationen auf anderem Wege entfesselt oder 

 moglich macht. 



If Loeb has found evidence that the permeability of the egg increases on 

 fertilization, or fatty acid treatment, I would be very glad to have my 



' Amer. Jour. Physiol., vol. 29, p. 295, Appendix II. 



2 McClendon. Biol. Bull., vol. 22, p. 113. 1912. 



5 Loeb, J. Science, n. s., vol. 32, p. 412. Sept. 23, 1910. 



< Loeb. LTniv. of California Publications, Physiol., vol. 3, No. 11, p. 81. 1908. 



' Loeb. Die Chemische Entwicklungserregung des tierischen Eies. Berlin. 1909. 



