1904] SHULL—PLACE-CONSTANTS FOR ASTER 347 
1. Bracis—The frequency polygon for the bracts is shown in 
ig. 8. The mean value is 38.597 +-.189, and a number of empirical 
modes are present. Some, if not all, of these are doubtless due to 
the smallness of the number of heads counted. It will be noted 
September October 
2 14 16 18 ee 2s 25. 2728 30 2 i J 
"yi es as 
oes SG : 
ettth ae 
s2ag i 
—h—— ef Be” % 
inane T 
PALLY +. 
WE y = : XN : :., 
—_— HH Zs 5 ®, TNyiicl p Eos Et 
ry Ht Sei iL a 196 0 
Toy oer 2 ee a ial eta SS 
eer aN se \ > Trt 
L ae ee =e ™~ Bracts 190 yt 
ct+rtrt a ‘ | 
— gag \ L, a% 1903, 
ret tt TT Nee y 
toe + 4 14 
PAC td gore 
} Pree racts 
~~ st +H YH" YH a pj} +t 
TEES geUREEe —~ aBaee 
au = a ee Ses 
area Hy 4 
eet tr ttre & = > 
& tH {WY |" Lt | oe as San Sa 
SPS soos feseuueeeeees 
TENSE E “> ~ 1900 HH 
Suenos a t 7 el 
EE : coo 
oH Rac. ea 
Fig 
I—~C : 
fom the a showing the changes in the mean numbers of parts 1n the heads 
“MIS, 190 NG fo the end of the season, and the difference between the two collec- 
and 1903, 
tat 
om se Prominent modes are those which lie below the mean 
S er ent .. © may speak of skewness in multimodal curves, mgt 
We exhibits to a strong positive skewness. The breadth of t 
€ eye the great variability, which may be express¢ 
