J. Y. Simpson 
403 
The correlations between divided individuals have been determined for length, 
breadth, and the index ^'"^'^'^^^ _ 
length 
The compilation of the correlation tables was undertaken, and the computations 
connected with them were performed by Miss Lee, D.Sc, whose assistance I would 
gratefully acknowledge. The values obtained are given in the following tables : — 
TABLE II. 
Constants of the Series. 
Organ 
Mean 
Standard 
Deviation 
Length 
Breadth 
Index 
229-0.50 
68-125 
29-913 
19-152 
9-155 
4-029 
TABLE III. 
Correlations. 
Organs 
Correlations 
Lengths of 1st and 2nd Members 
Breadths of 1st and 2nd Members 
Breadth of 1st and Length of 2nd Member 
Index of 1st and 2nd Members 
Length and Breadth of 1st Member 
•914 + 0-011 
•782 ±0-026 
•447 + 0-054 
•664 ±0-038 
■421+0-055 
These values are remarkably high, compared with the homotypic values 
obtained by Professor Pearson in a large number of cases among animals and 
plants. Among the causes which obviously tend to raise the apparent correla- 
tion between the members of a pair resulting from division are (1) differences 
in the length of time which elapsed between division and measurement, involving 
the inclusion in the Table of individuals differing considerably in age; (2) differ- 
ences in the treatment of different pairs, which the most careful culture cannot 
■wholly prevent. The second of these causes can hardly be allowed for; an attempt 
was however made to provide a means of estimating the effect of the first, by 
measuring a smaller series of individuals at known intervals of time after division, 
and again at a known interval of time after the first measurement. The difficulties 
of restoring the individuals to normal conditions of life after a first measurement 
were so great that the series obtained is small : and the measurements were made 
at a different time of year. The principal difficulty is associated with the artificial 
means employed to quiet the protozoa so as to admit of accurate measurements 
being made. Many methods have been suggested, from the use of narcotics down- 
