CELL DIVISION IN EGGS OF CREPIDULA. 521 



was put into the legs of the boots and into this the wires from one or more dry 

 batteries dipped. The impressed voltage varied from % volt to 1 volt, but the 

 amperage was not measured. Under the conditions described it is uncertain 

 to what extent the current actually went through the eggs. When the trough 

 was filled with eggs and the amount of water was very small many of the eggs were 

 penetrated, but in general the resistance of the eggs was so much greater than that 

 of the surrounding water that many of the eggs were left in a normal condition, 

 and it may be assumed that few of the eggs were penetrated by the full strength 



of the current. 



Nevertheless many eggs show by certain unmistakable signs that they were 

 penetrated by the current. Not infrequently eggs were killed outright and 

 even fragmented or disintegrated; in some cases they were coagulated together 

 into a single mass. Where the injuries were less gross, but where the eggs w«e 

 undoubtedly killed there is no distinct separation between protoplasm and oik. 

 and the chromatin of the resting nuclei, the chromosomes and spindle filers of 

 division stages have dissolved more or less completely (figs. 80-86). In tome 

 cases the chromosomes have disappeared from the amphiaster, leaving th< 

 spindle fibers and polar rays intact (fig. 90). Where the injury was less severe 

 the substances of the egg may be stratified by the current, the nuclei and cyto- 

 plasm being driven to one pole while the yolk remains at the other. Strands 

 and streamers of cytoplasm may extend through the yolk or over its surface, 

 thus indicating the direction of movement, as in figs. 88, 91. This dislocation 

 of ooplasmic substances is in many respects similar to that produced by cen- 

 trifugal force. In this respect my results confirm those of Roux, Pcntimalli, 

 McClendon, et al. This stratification is the result of convection currents within 

 the cell and it throws little if any light upon the nature of the mitotic figure. 

 For this reason it seemed desirable to employ weaker currents and at the same 

 time to take such precautions as were possible to insure the current p< net rating 

 the eggs. In Exp. 1120 a current of 1 mil. amp. was passed through the trough 

 between porcelain-boot electrodes for 45 min., but this current was so weak that 



it produced no effect whatever upon the eggs. 



Later experiments with the electric current were performed under the follow- 

 ing conditions: The eggs, either within the capsules or after they had been liber- 

 ated, were placed on a graphite plate, which had previously soaked in water the 

 water was drained off and a second graphite plate, similar to the first, was laid 

 over the first, the two being separated by cover glasses of a thickness about equal 

 to the diameter of the eggs. Each plate was connected with the pol< of a dry 

 battery, or of several dry batteries in circuit. The strength of the current used 

 varied from 50 mil. amperes to 1 mil. ampere, but the exact area covered by tne 

 eggs on the graphite plate was not measured in every case. In f neral ^°* ev \' 

 the eggs covered an area about 3 cm. square. With a current of from 40-50 mil. 

 amperes which was used in experiments 1100-1103, the eggs were coagulated 

 almost at once and stuck fast to the anode. In all later experiments, the current 







