128 REPORTS ON INVESTIGATIONS AND PROJECTS. 



eating that one effect of the carbonated sea-water is the removal of the jelly. 

 For Tripneustes carbonated sea-water 10 minutes, hypertonic i hour, is best. 



By Kohlrausch's method, the electric conductivity of the eggs of Tox- 

 opneustes zvas found to increase when they were fertilised or stimulated by 

 acid to develop. This experiment was repeated a great number of times 

 and every possible precaution against error taken. The temperature did 

 not vary one-tenth of a degree, the jelly was washed off of the eggs and 

 they were precipitated in the conductivity vessel to exactly the same level 

 for each reading, and the current used would not stimulate nerve. It was 

 feared that the pushing out of "fertilization" membranes would increase the 

 conductivity. Eggs that had remained so long in sea-water that they could 

 be caused to develop without the pushing out of membranes were chosen in 

 many experiments, yet these showed a marked increase of conductivity on 

 beginning development (too great to be the result of C0 2 formation, though 

 perhaps not so great as in those that pushed out membranes). 



At Woods Hole it was found that on passing a strong electric current 

 through an egg the "fertilization" membrane was pushed out toward the 

 cathode, whether it previously lay in contact with the egg or not. Some 

 eggs were found to develop without even the formation of a "fertilization" 

 membrane. However, some critics may yet object to Kohlrausch's method, 

 since masses of eggs must be used and there remains a little sea-water be- 

 tween the eggs. Therefore fertilized and unfertilized eggs were placed in a 

 molecular solution of sugar and examined under the same cover-glass under 

 the microscope. The fertilized eggs were smaller than the unfertilized 

 eggs, indicating that the salts had passed out of the fertilized eggs, decreas- 

 ing the internal osmotic pressure and causing plasmolysis. If a gradually 

 increasing electric current be passed through such a preparation, the unfer- 

 tilized eggs begin to disintegrate sooner than the fertilized eggs. This indi- 

 cates that there are fewer ions in the fertilized eggs or that the ions are not 

 retarded as much by the membranes. This disintegration commences first 

 at the anode end, indicating that the anions can not pass through. This sug- 

 gests that development is caused by increase in permeability to anions, allow- 

 ing the OH ions of the sea-water to enter the egg and accelerate oxidations. 



The freezing-point of the sea-water at Tortugas was found to be — 2.03 ° 

 C. and that in Boca Grande channel to be — 2.05 ° C. 



Researches Performed at Tortugas, July 1910, by B. Newton Harvey, 



Columbia University. 



PERMEABILITY. 



During the summer of 1909, at Tortugas, a study of the mechanism of 

 membrane formation in sea-urchin eggs was begun, in hope of finding out 

 the nature of the process, for there is no doubt of its importance in connec- 

 tion with the starting of development of unfertilized and fertilized eggs. 



Reasoning from the close analogy to muscle stimulation, the fact that the 

 starting of development (more specifically membrane formation) is essen- 

 tially a stimulus reaction, in which the result is dependent on the composition 

 and structure of the part stimulated, independent of the kind of stimulus^ it 

 was concluded that the same change must occur in an egg (which leads to its 

 development) as occurs in a muscle and leads to its contraction. This change 

 appears to be an increase in permeability of the bounding surface of the cell 

 to some reaction product or products, whereby the chain of reactions, in 



