566 



SCIENCE 



[N. S. Vol. XXXII. No. 825 



of alkali takes place just the same when swell- 

 ing is prevented (for a short time) by the 

 addition of cane sugar to the sea water. 

 Either the NaOH fails to enter normal eggs 

 or only enters so slowly that it is neutralized 

 within the egg. Since the number of eggs is 

 very small compared with the bulk of alkaline 

 solution, and the alkali would continue to dif- 

 fuse in, so long as neutralized, it would re- 

 quire an enormous production of acid on the 

 part of the egg to take care of the NaOH en- 

 tering. For this reason the first alternative 

 seems more probable. 



By treating eggs stained in neutral red with 

 stronger and stronger concentrations of NaOH 

 in 0.6 m NaCl the alkali penetrates more and 

 more rapidly. If a concentration of JSTaOH 

 which enters the egg in twenty minutes be one 

 quarter saturated with chloroform, the NaOH 

 enters in ten minutes. One quarter saturated 

 chloroform in NaCl has no visible effect on 

 the eggs even after one hour. The effect of 

 dilute solutions of chloroform, which fail to 

 cytolyze, on the eggs of Hipponoe, is to in- 

 crease their permeability to NaOH. Indeed 

 it may be shown in the same way, that small 

 concentrations of chloroform increase the per- 

 meability of the leaf cells of Elodea, showing 

 active protoplasmic rotation, and that the nor- 

 mal impermeability is again regained when 

 the leaves are returned to tap water. The 

 above statements are equally true for ether. 

 It is obvious that the number of substances 

 whose effect on the cell surface we may test 

 in this way is limited, for most of them com- 

 bine with NaOH. 



Thus one of the most effective substances 

 for producing artificial membranes, chloro- 

 form, increases the permeability of the egg 

 for alkali. By comparing the time it takes 

 for the stained eggs, fertilized and unfertil- 

 ized, to change from red to yellow, in the 

 same solution of NaOH, it is found that just 

 after fertilization (2-5 minutes) the egg is 

 much more permeable to NaOH, despite the 

 fact that it is surrounded by a fertilization 

 membrane. While my experiments were being 

 performed I was unaware that Loeb had been 

 studying the relative injurious or destructive 



action of alkali on the fertilized and unfertil- 

 ized eggs and had found the former to be most 

 quickly injured. My results with red-stained 

 eggs show that the injurious action is actually 

 due to the penetration of alkali. The same is 

 true if we form the membrane artificially by 

 treatment with acetic acid (in Asterias). In 

 the only series of experiments performed, with 

 Toxopneustes eggs, between ten and fifteen 

 minutes after fertilization the eggs return to 

 the same condition of permeability, with re- 

 spect to alkali, as the unfertilized. There ap- 

 pears to be a second increase at the time of 

 first cleavage. 



Thus far I have found no dye which is 

 harmless for eggs and at the same time 

 changes in color in acids. The egg of Hy- 

 dractinia, however, contains a natural green 

 pigment which becomes red in HCl but not 

 green again in alkali. The color change also 

 takes place when the eggs are slowly heated. 



If we place unfertilized Hydractinia eggs in 

 50 c.c. sea water -|- 3 c.c. n/10 HCl it takes 

 half an hour for the green pigment to become 

 red. If first treated with chloroform-saturated 

 sea water, and then placed in the acid sea 

 water the color change is almost instantane- 

 ous. Thus the normal eggs are relatively im- 

 permeable to HCl. Unfortunately carbonic 

 acid is too weak to affect the color of the 

 green pigment, and we can not test the perme- 

 ability of fertilized and unfertilized eggs to 

 CO,. The end of the breeding season has 

 made a comparison of the entrance of HCl 

 into the fertilized and unfertilized eggs im- 

 possible. 



A phenomenon that occurs, if the treat- 

 ment of an egg with chloroform and many 

 other membrane-forming substances be pro- 

 longed, is cytolysis. It is characterized by 

 the swelling of the egg and the decomposition 

 of the visible granules which appear to fuse 

 to larger more liquid spheres, with a loss of 

 their natural pigment or of their stain if first 

 placed in a solution of neutral red. By the 

 use of the centrifuge, which brings about 

 such a distribution of the chemical constit- 

 uents of the egg that we can readily see ex- 

 actly what happens to each of them, it may 



