70 



SCIENCE 



[N. S. Vol. XL. No. 1019 



The above-mentioned sandstones, instead of 

 " being overlain to the vs^est by the light- 

 colored sandstones of the lone formation," 

 are in reality stratigraphically higher. These 

 sandstones have been worn away from most of 

 this area and only a few residuals remain. 



After this great erosion, andesitic tuffs and 

 tuff breccias covered all. During the Pleisto- 

 cene and Recent time much of the andesitic 

 material has been removed re-exposing the 

 older rocks beneath. 



The lone has been repeatedly correlated 

 with the Auriferous gravels of the Sierras and 

 the upper portion with the rhyolitic tuffs. It 

 can no longer be doubted that the lone is of 

 the same age as the Rhyolitic tuff and the 

 Auriferous gravels, and since the lone is 

 clearly Tejon-Eocene, the Auriferous gravels, 

 their correlative, must be upper Eocene, at 

 least in part and the land equivalent of the 

 marine Tejon. 



Roy E. Dickerson 



THE INCREASE IN PERMEABILITY OF THE FROG's 



EGG AT THE BEGINNING OF DEVELOPMENT 



AND THE PRESERVATION OF THE 



LIFE OF THE EGG ^ 



Three years ago, it was observed that the 

 unfertilized frog's egg could be made partheno- 

 genetie by a momentary electric shock, and 

 reasons given for supposing that the electric 

 shock (or the spermatozoon in normal fertili- 

 zation) increased the permeability of the egg.'' 

 Recently, I proved this supjwDsition to be cor- 

 rect. The permeability of the unfertilized egg 

 to NaCl was found to have increased on stimu- 

 lating the egg with an electric shock (which 

 caused it to begin normal development). 



Several methods were tried for the quanti- 

 tative estimation of sodium ions, but the re- 

 sults with such small quantities would not be 

 considered trustworthy had they not tallied 

 with the more certain results on the deter- 

 mination of chlorine ions with the nephelom- 

 eter, and only the latter will be described here. 

 The technique was as follows: 



1 Preliminary note. 



2 Meaendon, Science, N. S., Vol. 33, p. 629. 



A " pregnant " female of Rana pipiens was 

 washed in alcohol and then in water, pithed 

 and opened. The eggs were removed from the 

 oviducts without mechanical injury or con- 

 tamination with blood or lymph. These eggs 

 were washed 10 minutes in a large volume of 

 HjO^ and divided into two exactly equal 

 masses. Each mass was placed in 30 e.c. of 

 H„0 and allowed to remain for 30 minutes 

 while the jelly swelled. The water that had 

 not been taken up by the jelly was analyzed 

 and the Na + said CI — found to be the 

 same for both lots. Then lot 1 was stimulated 

 by an electric shock from clean platinum elec- 

 trodes* and lot 2 used as a control. 20 e.c. of 

 H,0 were added to each lot and at the end of 

 one hour this water was analyzed. There was 

 more Na+ and CI — in the water from the 

 stimulated eggs than the control, the ratio of 

 CI — being 10 to 7. This is a very small 

 difference, but it must be remembered that the 

 salt in diffusing out of the egg is held for 

 some time by the "fertilization membrane" 

 and the thick jelly surrounding the egg. Con- 

 sequently 30 C.C. of H,0 were added to each 

 lot and allowed to remain eight hours to give 

 time for the salts to diffuse through the jelly. 

 There was now found three times as much 

 CI — that had diffused out of the stimulated 

 eggs as had diffused out of the control. 

 Whether this increase in permeability is the 

 cause of development has not been determined, 

 but it is not restricted to the frog's egg, since 

 I found the same true of the sea urchins' egg,° 

 a fact which has been confirmed by Gray^ at 

 Plymouth. 



The unfertilized frog's egg placed in fresh 

 or distilled water continues to swell until death 

 ensues. This death is probably caused by the 

 swelling, and the latter by the osmotic pres- 

 sure of the soluble substances contained within 



3 HjO means water redistilled in quartz. 

 * In about one minute all of the eggs had turned 

 the black pole upward; 3 hours later the first 



s McClendon, Amer. Jour. Physiol., 1910, Vol. 27, 

 p. 240. 



6 Gray, Jour. Marine Biol. Assw. U. K., 1913, 

 Vol. 10, p. 50. 



