Raymond Pearl 
57 
breadth dimensions, the variation in the length-breadth index has also been 
studied. 
Series A included 201 individuals and Series B 175 individuals. Larger 
numbers would have been measured but for the fact that the work on Ghilomonas 
was interrupted by other work which had to be carried on while the material was 
available. With the degree of variation exhibited by Ghilomonas, however, these 
numbers lead to reasonably small values for the probable errors of the constants 
and hence we are able to reach definite conclusions. 
In the calculation of the constants the ordinary biometrical methods were 
followed. Sheppard's corrections for the moments were used in all cases. 
The work was done in the Zoologisches Institut at Leipzig, and it is a pleasure 
to express my thanks to Professor Carl Chun and Professor Otto zur Strassen for 
so kindly placing the facilities of that laboratory at my disposal. I am also 
greatly indebted to the Carnegie Institution for a grant, during the tenure of 
which this investigation was carried out. 
Results. 
The data for the length and breadth of the individuals measured are exhibited 
in Tables I and II. Table I gives the data for Series A, that is, the individuals 
living under unfavourable conditions, while Series B including the individuals living 
under favourable conditions is efiven in Table II. 
TABLE I. 
Length and Breadth of 201 Individuals of Ghilomonas paramecium. 
Unfavourable conditions. 
Breadth in mikrons. 
Series A. 
a 
o 
'a 
a 
bjo 
OS 
05 
•:=^ 
1 
1 
1 
00 
d 
00 
1 
1 
1 
1 
i 
"-I 
1 
<?! 
1 
Totals 
j> 
Co 
o 
14-0—lJf-9 
1 
1 
15-0--15-9 
16-0— 16-9 
1 
1 
17-0— 17-9 
1 
1 
2 
4 
18-0— 18-9 
2 
1 
4 
3 
2 
1 
13 
19-0— 19-9 
1 
1 
2 
1 
6 
1 
12 
20-0— 20-9 
1 
2 
4 
3 
8 
10 
3 
2 
33 
21 -0—21 -9 
1 
3 
8 
5 
5 
1 
23 
22-0— 22-9 
1 
5 
8 
7 
3 
1 
1 
26 
23-0— 23-9 
1 
10 
7 
6 
2 
3 
29 
2^-0— 2^-9 
5 
3 
3 
3 
4 
18 
25-0— 25-9 
1 
6 
3 
3 
2 
2 
1 
18 
26-0— 26-9 
2 
3 
4 
2 
1 
3 
15 
27-0— 27-9 
1 
1 
3 
5 
28-0— 28-9 
1 
2 
3 
Totals 
2 
7 
9 
12 
27 
51 
37 
26 
11 
10 1 8 
1 
201 
Biometrika v 
