530 Andrews . — The Effect of Gases on Nuclear Division. 
4. Resting nuclei in a 1 per cent, or stronger solution of ethyl ether 
cannot begin division. In 1, 2, 3, 4 , 5 > and 6 per cent solutions of ethyl 
ether, nuclei in the prophase stage finished division and formed a cell -wall, 
both processes taking place in somewhat less time than the controls. In a 
7 per cent, solution of ethyl ether no advance towards completing division 
was made. 
5. In a | per cent, solution of chloroform water, nuclei in the pro- 
phase stage divided and a cell-wall was formed. Resting nuclei could not 
divide. 
6. Nuclei in the prophase stage can divide at 1*5° C. Resting nuclei 
cannot divide below 7 0 C. 
7. Nuclei in the prophase stage can finish dividing, but form no cell- 
wall at 34 0 C. 
8. Nuclei in the prophase stage in a J or J per cent, solution of 
ammonium carbonate can divide and form a cell-wall. In a 1 per cent, 
solution of ammonium carbonate nuclei in any stage cannot divide. 
9. Whenever nuclear division occurred in these experiments it was 
always by karyokinesis. 
10. These experiments show that, contrary to the opinion of Demoor, 
the nucleus cannot divide independently of the protoplasm, and that if the 
protoplasm is killed or temporarily disabled the nucleus is also soon like- 
wise affected. The only reason that the nucleus continues to divide is that 
a little time is naturally necessary for the reagent to affect the protoplasm 
or to reach the nucleus. Even when the activity of the protoplasm just 
ceases, nuclear activity ceases also. It is just as impossible for the nucleus 
to divide after the protoplasm has been killed or its activity annulled as it 
is for either the nucleus or protoplasm when separated to continue to live, 
no matter how perfect all other conditions may be. 
In conclusion it is my pleasant duty to express my thanks to Prof. 
Pfefifer for his constant kindness and advice in these experiments. 
