236 A Biometrical Study of Conjugation in Paramecium 
We may turn now to the character breadth, for which Table VI. has been 
formed on exactly the same plan as Table V. for length, except that the short 
series B and D are not included. They show essentially the same relations as 
A and C and, in view of the small number of individuals, it seems hardly worth 
while to publish the results from them in detail. 
TABLE VI. 
Differentiation of Gonjugants from Non-Gonjugants in Breadth. 
Series 
Group 
Mean 
Standard 
Deviation 
Coefficient of 
Variation 
A 
)) 
Non-Conjugants ... 
Gonjugants 
52-827 + -27.3 
44-.371±-194 
5-870 ±-193 
4-170±-147 
11-112 + -370 
9-398 ±-312 
); 
Absolute Difference 
Relative „ 
8-456 + -335 
16-0 % 
1-700 + -237 
28-96 % 
1-714 + -484 
15-4 7„ 
c 
Non-Conjugants ... 
Gonjugants 
54-208 + -280 
43-158 ±-162 
5-905 + -198 
3-414±-115 
10-894+ -370 
7-910 ±-267 
)> 
1> 
Absolute Difference 
Relative „ 
11 -050 +-324 
20-4 % 
2-491 + -229 
42-2 7„ 
2-984+ -456 
27-4% 
From this table it is seen that in breadth the same kind of differences occur 
between conjugants and non-conjugants as have already been found for length. 
The conjugants are markedly narrower, and less variable in this character than 
the non-conjugants. In no case is there any doubt about the difference between 
conjugants and non-conjugants being significant. The differences are propor- 
tionately somewhat larger for breadth than for length, but it should be kept in 
mind that a part of this excess in relative breadth differences, has the simple 
explanation that the conjugants have their oral surfaces somewhat flattened, as a 
result of the union (see above, p. 222). This results in an artificial lowering of 
the mean and variability in the breadth distributions for conjugants. 
Some information regarding the extent of this decrease in breadth due to 
the conjugation process itself may be gained if we look at the matter in another 
way. Assume, for the moment, that the selection of conjugants is a selection 
based on length alone, and that breadth is only different in conjugants from what 
it is in non-conjugants because it is organically correlated with length. Then 
clearly the mean breadth of conjugants would be the same as the mean breadth 
of a group of non-conjugants having the same mean length as the conjugants. 
Now, for series A and G, the characteristic equations* relating breadth to length 
in the non-conjugants are as follows : 
Series A, Non-conjugants. B = •2224i + 10-576, RE. = 3-199, 
G, „ 5 = -18977/ + 14-493, P.E. = 3-145, 
* These are calculated by well-known methods given by Pearson, Phil. Trans. Vol. 187 A, pp. 
253 — 318, and also in convenient form by Yule, Jour. Buy. Stat. Soc. Vol. 60, pp. 1 — 44. 
