1900-1.] Dr J. Y. Simpson on Binary Fission of Ciliata. 409 
sets in. Finally, this degeneration further expresses itself in a 
sort of sexual hypersesthesia, causing sterile conjugations that 
inevitably end in the death of the partners. 
Now, Maupas determined that senile degeneration began in 
the case of Styl. pust. about the 170th generation or division, 
and that death ensued at the 316th. Similarly, cultures of 
Onychodromus became extinct after 330 generations, and so on. 
It is also an integral part of his theory that it is impossible to 
induce conjugation during the earlier bipartitions which cover a 
definite period of immaturity : in the case of Styl. pust. this 
extended to the 130th division. At the end of these earlier 
divisions — at the 131st in the case of Stylonichia — puberty is 
attained, and conjugation can be induced. This period of eugamy 
lasts over a definite number of divisions — until the 170th, as 
we know in the case of Stylonichia — when senile degeneration 
sets in, ending in death. 
The first thing that strikes one when examining Maupas’ tables 
of binary fission is their mechanical regularity. The following 
represents the first fortnight of the well-known Stylonichia 
pustulata table : — 
Date. 
Temperature. 
Individuals. 
1 
Number of Bipartitions. 
In 24 hours. 
Total. 
February 27 
16° 
1 
„ 28 
16 
2 
”i 
i 
March 1 
16 
4 
i 
2 
„ 2 
16 
32 
3 
5 
„ 3 
17 
147 
2 
7 
„ 4 
18 
483 
2 
9 
5 
18 
935 
1 
10 
He isol 
ated one of the £ 
)35. 
March 6 
19 
2 
1 
11 
7 
19 
8 
2 
13 
„ 8‘ 
18 
64 
3 
16 
9 
17 
230 
2 
18 
He isoh 
ited one of the 230. 
March 10 
17 
4 
2 
20 
„ 11 
17 
16 
2 
22 
„ 12 
16 
126 
I 3 
25 
