1908] DANFORTH—VARIATION IN DAISY 355 
leaves. Only too plants were examined to determine this rela- 
tionship, but among these specimens, which were collected at 
Norway in June, 1908, I found no exception to the rule that 
the direction of a set of 21 spirals in the disk is similar to the 
direction of the shortest line that can be drawn from any leaf on 
the stem to the next succeeding leaf. That is to say, if a stem was 
‘so held that any given leaf faced the observer, and it was seen that 
the next higher leaf on the stem was toward the left rather than 
toward the right, then a set of 21 left-handed spirals was invariably 
found in the disk. Of the too heads examined, the 21 spirals were 
found to be left-handed in 47 cases and right-handed in the remaining 
53 cases. Of course the direction of the leaf spirals varied accord- 
ingly. There can hardly be any indication of incipient species here, 
for the arrangement on the branches of large plants is, as frequently 
as otherwise, reversed in reference to the arrangement on the main 
Stem. I have been unable to trace the transition from the placing 
of the leaves to that of the flowers, except to notice the above-men- 
tioned correlation. 
The ray florets are placed, as one might expect, at the peripheral 
ends of these spirals. Each of the spirals in the set of 21 generally 
has a Tay floret at its end; and frequently there are no other rays, 
specially if the other set consists of 1 3 or 21 spirals. When there 
are 34 spirals in one set, however, and the head is large, the number 
of ray florets is frequently increased, when each of the 34 spirals 
May be terminated by a ray. This case, though common, is less 
frequent than the other. Instances frequently occur where rays do 
hot develop at the ends of some of the spirals, or (less commonly) 
where two rays develop on the same spiral. Heads that show more 
than 34 rays are of this class. In some of the Compositae, for 
‘xample in Erigeron, where the disk florets are arranged in no more 
Spirals than we find’ in the daisy, there are many rays; but in such 
fases several flowers of each spiral develop as rays, while in the 
daisy there seems to be but slight tendency for more than one flower 
to so develop. 
If the typical Chrysanthemum Leucanthemum shows as much 
tendency for developing more than one ray on some of the spirals as 
°es the var. pinnatifidum, it would seem hazardous to regard any 
