STOUT & Boas: STATISTICAL STUDIES IN CICHORIUM 447 
furnishes valuable clues as to whether the origin or evolution of 
different flower numbers per head is of continuous or discon- 
tinuous nature. 
When the data for an individual plant of chicory are massed 
there is most often a rather pronounced mode or maximum. A 
certain number of flowers per head on a plant occurs with greatest 
frequency. The modal number, however, is not the same for the 
various individuals of a mixed population or even of a race: for 
some individuals it falls on as low a number as 14; for others it 
falls as high as 22. In relatively few cases do the maxima fall 
on one of the primary numbers of the Fibonacci series and the 
grand maximum certainly does not thus fall. 
A consideration of variation within the individual (partial 
variability) shows that the number of flowers per head in chicory 
may range on a single plant from 7 to 31. The primary numbers 
8, 13, and 21 of the Fibonacci series are thus all represented on a 
single plant and the range extends almost to the next in order, 34. 
Furthermore, as a rule, all numbers between the extremes are 
represented on an individual. 'The variations within the individ- 
ual are certainly continuous rather than discontinuous, at least 
to the extent that there is no rhythmic discontinuity with jumps 
to one after another of a series of maxima. 
The questions of chance variation, differentiation, and sym- 
metry deserve special mention. In chicory, it is clear that the 
differences in number per head are not purely chance variations 
that are due to undiscoverable factors. As fully noted in the 
literature review above, nearly all the statistical studies, both in 
methods of collection and in treatment of data, have considered 
the variations in flower number to be purely chance; but the re- 
sults obtained in chicory suggest that there may be present 
sources of variation that are due to differentiation in the sense 
used by Pearson. The data here reported show that position is a 
factor influencing flower number. As terminals bloom before 
their immediate laterals, differences according to position appear 
in the course of the succession of bloom, giving intraseasonal 
partial variability. In this sense the more lateral and later- 
blooming heads are differentiated from the more terminal and 
earlier-blooming heads of the same plant. 
