Trifolinm Pratcnsc Quinque folium. 49 
tingiiished from the ordinary instances of the rare four- 

leaved clover. 
A glance at the table on page 38 will show that my 
race was only very slightly developed at first, and had to 
be brought to its normal type by isolation and selection. 
But in spite of this selection it is not so constant that it 
does not occasionally give rise to atavistic individuals. 
On the other hand individuals with a maximum develop- 
ment of the character of the race are from time to time 
produced. And these extremes are sometimes both found 
within the limits of a single culture. 
I observed this in 1894 with plants which had been 
raised from the seeds of a single individual in the third 
generation (1891, p. 38). The seed-parent in question 
had survived the winter and did not ripen its seed until 
the second year. In July, 1894, there was a large num- 
ber of strong plants of the same age, of which I chose 
the seven best for a detailed examination of their leaves. 
Some of the oldest leaves were already withered, the 
youngest not yet unfolded ; these were not recorded. Each 
of these seven plants was plotted in the form of a curve, 
one (Fig. 6 A) gave the normal curve of the race, an- 
other (B) was atavistic, whilst all the rest had their 
highest ordinate at 7. I have only given the mean value 
for these five (C). 
These three groups gave the following percentage 
of leaves with the number of leaflets written above them : 
Number of leaflets: 34567 Number of leaves counted 
A. Normal example: 17 16 37 14 16 172 
B. Atavistic example: 75 19 5 1 216 
C. Extreme variants: 12 9 22 17 40 97 1 
1 Mean number per plant. 
