428 Mr Udny Yule, Fluctuations of sampling 
frequencies in the individual compartments of the table are too 
small to shew close agreement between observation and theory, | 
but if the observed and calculated frequencies are totalled for all | 
sizes of litter, as in the bottom row of the table, the agreement | 
shewn is very close indeed—closer than would be found as a rule, | 
If Professor Pearson’s test be applied (Phil. Mag., July 1900, and | 
Elderton’s tables, Biometrika, 1.), x? = 0°780, P=0-94, or a worse | 
fit between observation and theory is to be expected 94 times out 
of 100. Reducing the cases for which the expectation is 50 per | 
cent. in the same way, I find the figures for all sizes of litters given 
in Table B. Here the agreement is not quite so good, as the | 
observed data for litters of five or more are irregular, but it is | 
quite fair. I find y?= 8-003, P = 0:238, or a worse fit might be © 
expected nearly one time in four*. The same data may be other- | 
wise dealt with by working out the percentage of albinos in every | 
litter and comparing the standard deviation of such percentages - 
with (pq/ H)?. I find: 
Data of Table A. ) 
HT = 3°53 ; s.d. theo. 23:04; actual 23°09 + 1:00. 
Data of Table B. 
H=473; s.d. theo. 22°98; actual 21°63 + 0°90. 
The agreement here is very close. 
TaBLE B. Waltzing mace x albino hybrids crossed with albinos. 
Observed numbers of litters with 0,1, 2,... albinos and numbers - 
calculated (as in Table A) from expectation 50°/,. Data from 
Darbishire, Biometrika, 1. ; 
Number of Number of litters |! Number of Number of litters 
albinos in albinos in 
ipter Observed | Calculated uber Observed | Caleulated 
- 0 6 6:14 6 iL Paas 4-48 
1 21 19:98 | 7 0 1:28 
2 30 31°71 8 1 0-26 
3 37 32°90 9 or more — 0:03 
4 18 23°41 
5 18 11°83 
Total 132 132-02 
Turning now to the data for peas (Pisum) tabulated by indi- 
vidual plants in the Second Report of the Evolution Committee 
* In calculating P the frequencies of 4 albinos and upwards in the first case, 
and of 6 albinos and upwards in the second, were grouped. 
