o 
464 BOTANICAL GAZETTE {JUNE 
seem to invite immediate attention the most important are: (1) the 
determination of the modes and degrees of variation, an investigation 
which alone can yield data for a more critical discrimination of plant 
categories.”* Equally forceful words were spoken by Dr. Davenport in 
his address as retiring vice-president of Section F of the A. A. A. S. at 
its Denver meeting. He said* “the science of variation is therefore 
one of those that we may hope to see established in this century. I 
feel convinced that statistical studies are first of all necessary to lay the 
foundations of the science.” ‘The recent establishment of the periodi- 
cal “ Biometrika” will do much to increase the general interest in this 
department of biological investigation. 
The specimens of Helianthus annuus selected for this study were 
growing on vacant lots in Stillwater, Oklahoma, forming there the 
typical sunflower waste-formation so characteristic of that region. 
Determinations of the number of ray flowers were made ona total of 
_ 1103 heads selected at random over the variousvacant lots. The follow- 
ing tabulation and curve of variation show the results thus secured. 
te : Ve ‘Ainis Percentage | 1, = Percentage Ab ta. 
Class; inthe alge | dividal i th ‘his Class rg si eed — Faden in this 
| class | class. -_| or a higher class class class | Or ahigherclass 
18 0.90 _ 100 29 16 I 11.78 
ode 1.99 — 99.09 30 26 2.35 10.33 
oe 2.08 97.09 31 15 7-97 
aS: 2.26 95.01 32 25 2.20 6.61 
a 1.99 | 92.74 a3 20 1.81 4-35 
26 2.35 — 90.75 34 25 2.26 #5 
40 3.62 88.39 35 0 ) (0.27 
50: 453 84.76 oO oO 0.27 
gUR IOS 80.23 of 0.09 0.27 
ce SrQr | 70.08 38 ° oe. 0.18 
Ce eee OP Sage ° o 0.18 
_ | be 26.38 41 0 0 0.18 
m1 380 | 275 0 (0 0.18 
ee 2.26 18.94 at 4 0.09 0.18 
ae 3.26 16.68 Pe ee oO 0.09 
: = “s Jape 45 ae 0.09 0.09 
: iro thes above tabulation and feqneuty. curve the following facts 
secured. The class having 21 ray flowers includes over 31 per cent. 
the individuals. Slig tly over 10 per cent. of all the individuals 
= tr Probleme and pomieeties:< of es bonay Science 
1 
of “ twentieth century. “Science 14: 319. cee 
