528 Andrews . — The Effect of Gases on Ntulean Division. 
the end of the prophase stage, finished division and formed a cell-wall as 
soon as the chromosomes had separated. The movement of the protoplasm 
was slightly accelerated for a short time, as was also the division of the 
nucleus, as shown by the control specimen. The daughter-nuclei, which at 
first were not regular in form, became so after a time. 
In a 6 per cent, solution of ethyl ether the nuclei finished cell-division 
and formed a cell-wall. An hour later the protoplasmic movement was 
still noticeable, but the daughter-nuclei appeared vacuolated and did not 
become round as usual. At the expiration of twelve hours the cells which 
had been left in this solution of ethyl ether were dead. 
In a 7 per cent, solution of ethyl ether the nuclei in the prophase 
stage made no advance towards completing division, and the protoplasm, 
which showed at first a feeble movement in the older cells, stopped in fifty- 
five minutes. When not left under the influence of a 7 per cent, solution 
too long, the nuclei began to divide again, but always by karyokinesis. In 
all the experiments with ethyl ether, as with the other reagents, it was seen 
that if the activity of the protoplasm was accelerated or retarded, or if the 
protoplasm was killed, the nucleus was in a short time likewise affected. 
My experiments further show that the nuclei of the staminal hairs of 
Trade sc antia virginica cannot, as stated by A. Nathansohn 1 , be made 
to divide amitotically through the influence of ethyl ether. It may, as 
just stated, only hasten slightly or prevent division according to the 
strength of the solution used. When sprays of Trade sc antia virginica , with 
cells of the right age for cell-division, are, as Nathansohn states, placed 
under a bell-jar in water along with a dish containing a 2-2*5 P er cent, 
solution of ethyl ether, the nuclei do not divide amitotically. Karyo- 
kinesis is only arrested, and begins again in a short time after admitting 
fresh air. 
V. Effect of Chloroform. 
When the cells of Trade scantia virginica were placed in a drop of 
a 3 per cent, solution of cane sugar and the air from a solution of chloro- 
form-water diluted one-half with water was drawn over the cells, the nuclei 
in the prophase stage completed division and a cell-wall was formed. The 
movement of the protoplasm, which finally ceased, recommenced when 
brought into fresh water after three hours. Resting nuclei in a solution of 
chloroform-water diluted one-half with water did not divide. The air 
drawn from pure chloroform, as expected, killed all cells. 
VI. Effect of Cold. 
It is impossible for a nucleus at -3 0 or -4° C. to divide under any 
circumstances, as stated by Demoor. Even at o° C. a nucleus cannot 
1 Jahrb. f. wiss. Bot., 1900, Bd. 35. p. 70. 
