124 MR. MILLER CHRISTY ON THE 
of flowers measured was too few to yield reliable results. In May 1922, I found 
that, of 25 short-styled flowers gathered in a wood, two measured 15 mm., three 17, 
five 18, three 19, ten 20, and two 22—an average of 18°9 mm.; while, of 25 long-styled 
flowers, one measured 14 mm., one 15, one 16, ten 17, five 18, five 19, and two 20— 
an average of 17:6 mm. and a difference of 1:3 mm. 
Burkill’s measurements, made near Scarborough *, showed that the depth was 
15-20 mm.; but he did not discriminate between the two forms. 
Knuth's measurements, made in Schleswig-Holstein T, gave an average of about 
20 mm. in both forms ; for he also did not discriminate. 
Cowslip.—The only measurements I know of are my own, made in Essex. In 
April 1916, I found that the average depth of ten short-styled flowers was 15:1 mm. ; 
that of twelve long-styled flowers, 15 mm.—a very small difference. In May 1922, 
I found that, of five short-styled flowers of the larger form which grows on hedge- 
-banks, one measured 15 mm., one 16, two 17, and one 18—an average of 16:6 mm. ; 
while, of nine long-styled flowers belonging to the same form, two measured 14 mm., 
three 15, one 16, two 17, and one 18—an average of 15:7 mm. and a difference of 
0-9 mm. On the same date, of 24 short-styled flowers belonging to the slightly 
smaller form which grows in meadows, ten measured 15 mm., one 16, ten 17, one 18, 
and two 19—an average of 16:3 mm. ; while, of 25 long-styled flowers of the same 
form, one measured 14 mm., thirteen 15, seven 16, two 17, and two 18—an average 
of 15:6 mm. and a difference of 0*7 mm. 
Oxlip.—As to the flowers of this plant, there are on record measurements by three 
trustworthy Continental observers. 
Errera’s measurements, made near Brussels in 1878 f, are the earliest and most 
reliable, being the result of the measurement of a very large number of flowers. 
They show that the average depth in short-styled flowers was 15:2 mm.; in long- 
styled flowers, 19:6 mm.—a difference of 1:6 mm. 
Miiller’s measurements, made in Germany §, show that the depth of short-styled 
flowers was 15-17 mm.: that of long-styled flowers, 12-14 mm.—a difference of 
.9 mm. 
Knuth's measurements, made in Schleswig-Holstein ||, are identical with Müller's. 
My own measurements, made in Essex, show that the average depth of seven 
short-styled flowers was 16:3 mm.: that of five long-styled flowers decidedly less, 
but the exact figure was unreliably recorded. 
While these results differ considerably among themselves, they suffice, 
nevertheless, to show clearly that the corolla-tubes of short-styled flowers 
are really, on an average, considerably (usually 1-3 mm.) deeper than those 
of long-styled flowers. 
* Journ. of Botany, xxxv. (1897), p. 186. 
T ‘ Flower Pollination,’ iii. (1909), p. 68. 
1 Rec. de l'Inst. Bot. vi. (1905), p. 229; and * Œuvres Bot.’ i. (1908), p. 242. 
$ ‘Fertilization of Flowers,’ p. 384 (1883). 
|| ‘Flower Pollination,’ iii. (1909), p. 65. 
€] Possibly, indeed, he is merely quoting Müller's figures. 
