IO2 RALPH S. LILLIE AND WARE CATTELL. 



comparison a number of observations were made with fully 

 mature eggs. The procedure was simple ; the current was passed 

 through a shallow layer of sea-water containing the eggs, and at 

 regular intervals portions of eggs were transferred to dishes or 

 watch-glasses containing sea-water. Afterwards they were ex- 

 amined. Fertilized and unfertilized controls were kept in all 

 cases. 



Our preliminary experiments with battery currents of moderate 

 intensity (one to twelve storage cells) gave uniformly negative 

 results, and in all of our later experiments we used the current 

 from the direct current generator of the laboratory. We were not 

 able at first to find suitable electrodes. The ordinary forms of 

 non-polarizable electrodes ("boot" electrodes) proved unsatis- 

 factory because of high resistance and the diffusion of ZnSO 4 into 

 the sea-water. When platinum electrodes were used the eggs 

 showed partial activation (membrane-formation) in some experi- 

 ments; but it could be shown (by first passing the current 

 through a layer of sea-water and then placing the eggs in the sea- 

 water without the current) that this effect was due to or at least 

 could be produced by the products of electrolysis. These 

 results indicated the need for an arrangement by which strong 

 currents could be passed through the layer of sea-water without 

 contaminating the latter by the electrode solution or products of 

 electrolysis; and after a number of preliminary experiments the 

 following method was devised. The wires from the direct current 

 line (no volts) were connected with two broad zinc plates each 

 immersed in a dish of saturated ZnSO 4 ; these dishes with the 

 plates constituted non-polarizable electrodes of low resistance. 

 A rectangular glass vessel containing the sea-water in which the 

 eggs were to be exposed was placed between the dishes. In the 

 experiments of each summer a single vessel was used throughout 

 the whole series; the dimensions in 1922 were 14 x 5.5 x 3.5 cm., 

 in 1923, 13.1 x 6.6 x 3.5 cm. The depth of sea-water was kept 

 constant as nearly as possible throughout each series, 0.4 cm. in 

 1922 and 0.5 cm. in 1923; the sectional area (from which the 

 estimates of current density were made) was thus 2.2 sq. cm. in 

 1922 and 3.3 sq. cm. in 1923. The current was conveyed through 

 the sea-water by massive bridges of agar jelly of the same width 



