I 66 RALPH S. LILLIE. 



engaged with the aim of determining the influence of the electric 

 current on cell-division in the eggs of Astcrias and Arbacia. 

 Solutions of low conductivity (non-electrolyte solutions with a 

 trace of sea water and isotonic with the latter) were used to 

 insure the passage of the current through the eggs. The results 

 of this investigation are incomplete and their publication is de- 

 ferred for the present. It was found, however, that the simple 

 action of the solutions upon the eggs presented certain interesting 

 peculiarities which form the subject of the following description. 

 The solutions used were molecular solutions (which are ap- 

 proximately isotonic with sea- water) of urea, glycerine, and cane- 

 sugar, especially urea, which has the least injurious action on the 



eggs- 



In these solutions neither starfish nor sea-urchin eggs are cap- 

 able of cleavage. Eggs transferred to m-urea-solution shortly 

 after fertilization remain living for several hours and nuclear divi- 

 sion continues, although more slowly than under normal condi- 

 tions. No complete cleavages occur, although many eggs, espe- 

 cially those of Astcrias, assume irregular or amoeboid forms. In 

 Arbacia a partial constriction may appear at the equator of the 

 egg if the transfer is made shortly before the time of the first 

 cleavage, but in the majority of instances no such signs of incip- 

 ient cleavage appear. 



The following is a record of a typical experiment : 



July 12. Arbacia eggs, fertilized at 10:27 A. M., were washed with m-urea and 

 transferred to loo c.c. of the same solution at Il:io A. M. At 11:35 the control 

 eggs in the sea- water wer^ beginning to segment ; in the urea- solutions no signs of 

 segmentation were visible, but a few eggs had become somewhat amoeboid in outline. 

 At H:55 a larger proportion of urea-eggs were amoeboid ; a certain number were 

 dumb-bell-shaped with a clear area (nucleus) in each enlargement, the division into 

 two halves remaining incomplete. The great majority of eggs showed no such signs 

 of incipient division. At this time the control eggs were in the 2- and 4-cell stages. 



Urea-eggs of this series were preserved in picro-acetic and sub- 

 limate-acetic fixing fluids, 1 at stages corresponding to the 2-, 4-, 

 8- and 32-cell of the control. Subsequent examination of 

 stained preparations showed that nuclear division had proceeded 

 in the urea-solutions although cytoplasmic division had been en- 



1 Boveri's picro-acetic and saturated aqueous mercuric chloride with 2 per cent, 

 glacial acetic acid. 



