250 



SCIENCE 



[N. S. Vol. XXXII. No. 816 



1. Certain intravitam stains were taken 

 more quickly and in larger amounts by fertil- 

 ized eggs than by unfertilized. Toxopneustes 

 eggs, both fertilized and unfertilized, were 

 placed in a weak solution of methylene blue 

 for three to ten minutes. The former were 

 always more deeply stained. The difEerence 

 was striking. That this was not due to the 

 greater oxidative activity of the fertilized eggs 

 was shown by staining unfertilized eggs and 

 then fertilizing part of them. These stained 

 eggs developed normally to swimming larvas 

 and preserved nearly the same color as the 

 unfertilized eggs of the same lot and treat- 

 ment. Unless very deeply stained before fer- 

 tilization they never approached the degree of 

 color of eggs fertilized before being stained, 

 both lots having been exposed to the dye for 

 the same length of time. 



It was observed that, while the mature un- 

 fertilized eggs stain faintly, immature eggs 

 with large germinal vesicles stain even more 

 deeply than fertilized eggs. It seems that the 

 process of maturation leads to lessened per- 

 meability to certain substances, and it may be 

 that fertilization restores the permeable char- 

 acter necessary for the exchanges lying at the 

 basis of cell division. 



The eggs behave toward the stain dahlia as 

 toward methylene blue. Bismarck brown and 

 neutral red, however, stain unfertilized Tox- 

 opneustes eggs the same as fertilized. 



2. Eggs treated with hypertonic salt solu- 

 tion to induce parthenogenetic development, 

 returned to sea water and then stained with 

 methylene blue were more deeply colored than 

 the untreated control. Great variations in 

 stainability were found in the same lot of eggs 

 treated as above. Those eggs which took the 

 deepest stain were found to be the ones which 

 divided soonest and developed best. Treat- 

 ment of unfertilized eggs with weak acetic 

 acid followed by return to sea water to induce 

 artificial membrane formation was found also 

 to increase the permeability of the eggs to 

 methylene blue. 



3. If fertilized and unfertilized eggs stained 

 equally with methylene blue were placed in an 



Engelmann chamber and a current of hydro- 

 gen passed over them, the unfertilized became 

 pale sooner than the fertilized. This may 

 have been due to the less oxidizing (greater 

 reducing) power of the former. 



If after both sorts of eggs became colorless 

 in the hydrogen, air was readmitted to the 

 chamber, no difference could be detected in the 

 time required by the two sorts of eggs to be- 

 come blue again. We are inclined to inter- 

 pret this as indicating that fertilized and un- 

 fertilized eggs are equally permeable to 

 oxygen. 



4. If a large mass of Arhacia eggs was fer- 

 tilized in a small volume of sea water and 

 allowed to settle, the water was always found 

 to be slightly colored with the egg pigment. 

 This was never observed in similar suspen- 

 sions of unfertilized eggs treated in the same 

 way except as to the addition of sperm. Some 

 or all of the eggs on fertilization must lose 

 pigment. Microscopic examination showed 

 some fertilized eggs less deeply pigmented 

 than others. This loss of pigment in fer- 

 tilized eggs seems to be due to their greater 

 permeability to their own coloring matter. 



5. One' of us showed last year that follow- 

 ing fertilization there was an increase in the 

 ability of the egg to catalyze hydrogen perox- 

 ide. It was suggested that this might be due 

 to an increase in permeability, and some ex- 

 periments were detailed confirmatory to this 

 view. The experiments tried this summer 

 have shown that any treatment which in- 

 creased the catalase action of the unfertilized 

 egg also increased its stainability by methyl- 

 ene blue. We therefore believe that the 

 greater catalytic activity of fertilized eggs is 

 an expression of their greater permeability. 



6. If weak iodine solution was added to 

 equal amounts of fertilized and unfertilized 

 eggs in separate dishes and starch was added a 

 few moments later, it was found that the 

 iodine had disappeared entirely from the sea 

 water surrounding the unfertilized eggs, while 

 the water surrounding the fertilized eggs still 

 gave abundant evidence of the presence of 

 iodine. The diiierence was very striking. 



'Lyon, Amer. Jour, of Physiol.. XXV., p. 199. 

 1909. 



