PART III. | THE MECHANISMS OF FLOWERS. 44] 
the flowers very abundantly and in a similar way. All other 
visitors come as stragglers. 
A. Diptera—(a) Syrphide: (1) Syritta pipiens, L.; (2) Ascia podagrica, 
F. ; (8) Eristalis sepulcralis, L., s. and f.p.; (0) Muscide: (4) Scatophaga 
stercoraria, L., s. and f.p., also several small Muscide. B. Hymenoptera— 
Apide: (5) Apis mellifica, L. $,s.; (6) Andrena parvula, K. 2, s. and e.p. ; 
(7) Halictus sexstrigatus, Schenck, 9, s. and c.p. 
326. VERONICA OFFICINALIS, L.—The flowers do not open so 
widely even in warm sunshine as do those of V. Chamedrys. In 
fully expanded flowers the upper and lower petals only diverge at 
an angle of 70° to 80°, and the two lateral petals at 90° to 100°. 
The two stamens, which are very thin at the base, project from the 
flower at an angle of 30° to 40° from one another, and from the 
style which stands below them. Insect-visitors touch the stamens 
and stigma with various parts of their bodies, and lead to cross- 
and self-fertilisation indiscriminately. In flowers kept in the house 
and protected from insects, the stamens bend inwards and down- 
wards as they begin to wither until they touch each other and the 
stigma, producing self-fertilisation. The thinning at the base of 
the stamens, which in V, Chamedrys was shown to assist insects to 
perform cross-fertilisation, is here seen to aid self-fertilisation only. 
A. Diptera—(a) Empide : (1) Empis livida, L., s., ab. ; (b) Syrphide: 
(2) Helophilus floreus, L.,s. ; (3) Syritta pipiens, L., ab.,s. B. Hymenoptera 
—Apide: (4) Halictus albipes, F., e.p.; (5) Bombus (Apathus) vestalis, 
Foure. ?,s.; (6) B. Barbutellus, K. 2, s,—this large bee seemed dissatisfied 
with the small amount of honey, for after visiting a few flowers it went off to 
Glechoma hederacea. See also No. 609. 
327. VERONICA spicaTA, L. (Thuringia).—V. spicata shows a 
remarkable tendency to vary between proterandrous and _pro- 
terogynous dichogamy. On many plants, the style protrudes 
before the flower is fully opened (6, 4), and curves downwards 
and ripens its stigma before the anthers dehisce (0, 5). On other 
plants, when the flower opens, the style is much shorter than 
the stamens (b, 1; 2), and only reaches its full length and 
ripens its stigma when the anthers have been emptied of their 
pollen (0, 3). 
On plants of both sorts, flowers not unfrequently occur whose 
styles ‘never reach their full development, but remain concealed in 
the tube ; and on some plants this is the case throughout all the 
flowers. These aborted styles are often double (6, 8). Honey is 
secreted by the fleshy base of the ovary (h, 6, 7); it lies in the 
