146 THE AMERICAN NATURALIST. [Vow. XXXVI. 
TABLE H. — CORRELATION OF Rays AND BRACTS AND OF Rays AND 
Disk FLORETS IN Four PICKINGS OF ASTER 
PRENANTHOIDES MUHL. 








117 CAPITULA, 143 CAPITULA, 139 CAPITULA, | 176 CAPITULA, 
OLLE COLLECTED COLLECTED | COLLECTED 
SEPTEMBER 27. SEPTEMBER 3o. | OCTOBER 4. | OCTOBER 8. 
SRM Bes EE EN ae ea EE : See See 
Rays and | p | 855044 | 833702 798642 | 803092 
Bracts (P.E. p| + .012237 + .012701 $ 015133 | + .013443 
ee ins coge Setar eer cerdo AORA EA 
Rays and p -573693 358909 353102 -545208 
Disk E. nid + .033347 + .042145 + .043050 + .012157 


Inspection of this table shows that the highest degree of 
correlation between the parts was found at the beginning of the 
flowering season, and that there was a constant fall for both 
bracts and disk florets until near the end of the season, when 
the coefficient of correlation again slightly increased. The 
increase in the coefficient of correlation between rays and 
bracts in the last collection was less than the « probable error ” 
of the determination, but that between the rays and disk florets 
had increased until its value was only .0284 less than in the 
first collection. 
V. Discussion or RESULTS. 
The species which have been chosen for this study are quite 
distinct, and although Aster puniceus L. and Aster prenanthotdes 
Muhl. belong to the same division of the genus, Aster nove- 
anglié L. is more distant from these, and Aster shortit Hook. 
belongs to a division which is separated in a marked degree 
from the others. Considering this wide separation, it is rather 
remarkable that there should be so close an agreement in the 
number of bracts in the four species. The lower limit of 
range varies from 28 to 30, the upper limit from 49 to 64, and 
the means from 36.8 to 44.5. With the bracts so nearly con- 
stant, there is a range in the mean number of rays from 14 in 
A. shortit Hook. to 42.8 in A. nove-anghe L., and yet the 
degree of correlation between rays and bracts is high in all 
