312 L. V. HEILBRUNN. 



The concentration of anesthetic which produces a marked 

 lowering of protoplasmic viscosity is the exact concentration 

 which prevents cell division. Lower concentrations produce less 

 decided effects on cytoplasmic viscosity and in these cell division 

 is more apt to occur. As the concentration of the anesthetic is 

 increased, the decrease in cytoplasmic viscosity becomes more 

 and more pronounced until suddenly a turning point is reached. 

 At this point gelation or coagulation occurs. Eggs subjected to 

 such high concentrations of anesthetic undergo a decided increase 

 in cytoplasmic viscosity. When these eggs are centrifuged at 

 high speed the cytoplasmic granules remain fixed and do not 

 move. Compared with normal eggs the protoplasm of these co- 

 agulated eggs is much more viscous. The concentrations noted 

 in the second column of the table are those which were found to 

 produce a sharp increase in protoplasmic viscosity. Such an in- 

 crease in viscosity is in general irreversible. In practically every 

 case the eggs did not recover. 



My results with ether agree fairly well with the older observa- 

 tions of Heilbronn 1 on plant protoplasm. Heilbronn's measure- 

 ments were made by timing the drop of starch granules. He 

 found that dilute ether solutions caused a decrease in proto- 

 plasmic viscosity; more concentrated solutions caused increased 

 viscosity. Heilbronn was inclined to associate anesthesia with 

 the more concentrated solutions, which caused a stiffening in the 

 protoplasm, a " Plasmastarre." Perhaps this is true for plant 

 cells, but it is rather difficult to decide when plant cells are anes- 

 thetized. Heilbronn found that the " Plasmastarre " was in gen- 

 eral reversible. 



In medicine cold is a well-known anesthetic. Low tempera- 

 tures also anesthetize sea-urchin eggs. With decreasing tem- 

 peratures the protoplasm becomes less and less viscous. Even 

 at 10 C. there is a noticeable difference as compared to room 

 temperature. At - -3 C. centrifuge tests both with fertilized 

 and unfertilized eggs showed a decided lowering of viscosity. 

 In such eggs cell division is prevented, although the eggs remain 

 uninjured. Temperatures somewhat lower than -3 produce 

 an increase rather than a decrease in viscosity. If the sea-water 



i Heilbronn, A., Jahrb. wiss. Bot., 1914, LIV., 357. 



