52 
Scientific Proceedings (42). 
In other cases regeneration of the micronucleus-holding fragment 
was completed in from twelve to eighteen hours. 
5. In cells cut from twelve to eighteen hours after division 
and after full size is attained, the results are similar to those on 
cells immediately after division. The micronucleus-holding frag- 
ment alone regenerates, the other fragment, containing only 
macronuclear material lives for several days but fails completely 
to regenerate. This result was obtained in twelve different 
cases. 
6. If cut just prior to division both fragments regenerate within 
24 hours, the one fragment containing only macronuclear material, 
the other, containing both macronucleus and micronucleus. The 
latter regenerates more rapidly than the former. One cell re- 
generates without a micronucleus. 
7. If cut during the early stages of division three completely 
regenerated cells result, one of which (the fragment cut off) con- 
tains no micronucleus. Division continues in the original plane, 
the result being one normal cell and one minute cell perfect in all 
respects save size. Regeneration of the micronucleus-holding 
cells is more rapid than that of the third fragment. This result 
was obtained in fourteen cases. 
If the cells are cut during the later phases of division the 
results are similar to those obtained by cutting immediately after 
division. One fragment regenerates, the other fails. This result 
was obtained in seven out of eight experiments on cells in this 
stage, the other one gave regeneration of both fragments. 
8. The experiment shows a considerable variation in the power 
to regenerate in this form; this power is lowest immediately after 
division, but it gradually increases with age after division until 
it reaches a maximum immediately before the next division and 
during the early phases of division. 
During division it decreases to a minimum in the later stages 
and immediately after division. 
9. The results might be interpreted by the assumption of a 
specific substance, possibly enzymatic in nature, which accumu- 
lates with age of the cell until a condition analogous to saturation 
is reached. With the formation of the new cell-organs this sub- 
stance, it may further be assumed, is exhausted and regeneration 
