On the Species of the Genus Primula in Essex. 201
I have been unable to observe this myself on more than one
or two occasions, although I have often watched carefully in
places where Cowslips grow in abundance. In April I saw
a specimen of B. venustus, Sm., visit several flowers on a
cluster near Saffron Walden, and in May an individual of
B. scrimshiranus visited others at Chignal. At Tilbury
(near Yeldham) on May 1st last I saw a Brimstone butterfly
searching for flowers on a roadside bank. It visited a
Cowslip, took a considerable flight, and then returned and
visited ten more Cowslip-flowers in succession, after which
I lost sight of it. Thus I have seen this insect visit all our
Essex species of Primula.
As Mr. Darwin says (p. 21), the flowers of the Cowslip when
insects are altogether excluded are perfectly sterile. On April
28th I transplanted some plants with unopened flowers to
my garden, and covered them with gauze. They remained
open for want of fertilization an unusually long time, viz., to
nearly the end of May. At the end of June I found that
six s. plants bore ten umbels, and six 1. plants bore eight,
but not a single seed or capsule had been set in either form.
The following year, being uncovered, they all produced an
abundance of seed.
Of the Oxlip (P. elatior, Jacq.) but little remains to be said,
as I have already spoken of it largely in other places. Its
time of flowering is intermediate between that of the Primrose
and the Cowslip, although it varies of course a little according
to the season.48 The tendency to flower in the autumn is
48 Thus on March 18th, 1880, I found it just coming into flower in a
wood at Tilty; by the beginning of April the flowers had reached per-
fection ; by the 23rd many had withered; and by the end of the first
week in May they were almost entirely over. The spring of 1881 was a
very late one. On March 17th I could only see one or two flowers open,
and on the 27th scarcely any in a wood where there were plenty at the
same date in the previous year. On April 6th I noted them as being
"backward and stunted—not nearly full out," though they reached
perfection at the end of March the year before. Warm weather then
came, and they were at their best about the 20th. Then cold winds and
snow withered up many, though some, I believe, remained out until the
middle of May. In 1882 the spring was a very forward one. As early as
the 12th of February I found a plant bearing single flowers partly open,
P