External Conditions and Manuring. 319 
I counted the sepals of all the flowers. There were about 
2500 on the manured bed, and about 1500 on the un- 
manured. Amongst them were many with live and four 
sepals, and about 20 with 3, but none with fewer than 3 
or more than 5. Here again, a pronounced half curve 
was the result. I have reckoned together the proportion 
of 3-4-merous flowers for the individual counts, and at 
each stage in the counting collected all the flowers which 
had opened since the preceding one. The counts were 
made when possible every fourth day, or, when the num- 
ber of flowers was too small, at greater intervals. The 
result was as follows : 
PROPORTION OF 3-4-MEROUS FLOWERS IN %. 
June July Augus. 
Day: 19 23 27 159 13 17 21 25 29 2 
Manured: 7 13 24 28 34 39 50 65 49 49 43 27 % 
Unmanured: 7 20 33 39 42 49 46 44 % 
We see that the proportion of anomalies increased 
on both beds gradually throughout the summer, reached 
its maximum in the second half of July, and then sank 
again. On the manured bed, how r ever, this proportion 
amounted to 65% of the whole and on the unmanured 
bed to 49% of the flowers counted (160 and 224 flowers 
in the two cases respectively). In this case, therefore, 
both the periodicity and the relation to the external con- 
ditions are in all essentials the same as in the case of the 
white clover. In this latter case a plant which I had 
raised from seed served as material ; but in that of 
Potentilla a specimen which I had collected in the field. 
I shall now deal as briefly as possible with a series 
of further instances, emphasizing as before that the ex- 
ternal influences have the results in question only when 
the particular characters are already present in the semi- 
