PART III. | THE MECHANISMS OF FLOWERS. 497 
that supposing that a bee thrusts its head 5 mm. into the wide upper 
part, a proboscis 10 to 12 mm. long is needed to reach the honey. 
Visitors : A. Hymenoptera— Apide: (1) Bombus hortorum, L. 8 ? (18— 
21), very ab., sucking normally ; (2) B. agrorum, F. 9 (12—15), do.; (3) 
B. terrestris, L. 9 (7—9), bores through the corolla close above its bend, either 
piercing it with its maxillz or biting a hole with its mandibles ; (4) B. Rajcllas: 
Ill. § (10—11), steals the honey through holes bitten by B. terrestris, B. 
Diptera—Syrphide : (5) Rhingia rostrata, L. (11—12), fp., after trying i in vain 
to reach the honey. See also No. 590, I11, 
362. LAMIUM PURPUREUM, L.—The tube is only 10 to 11 mm. 
long, and for the upper 4 to 5 mm. it is wide enough to admit the 
head of a small humble-bee. The hive-bee, though its pro- 
boscis is only 6 mm. long, is thus enabled to suck the honey. 
Sprengel calls the plant proterandrous ; but in all the flowers 
which I have examined the stigmas and anthers developed 
simultaneously, though at first the angle between the two stigmas 
was less than it afterwards became, and the lower stigma stood at 
first above or between the anthers, but afterwards bent down 
below them. To decide whether the stigma is already capable of 
fertilisation when the flower opens, I set a plant of L. purpwreum 
in a pot (April 26, 1871), and removed all the flowers and capsules 
already present on it. Next morning five flowers had just opened ; 
in each I bent back the upper lip and the four anthers, and cut the 
latter off ; I then placed upon the two stigmas (the lower of which 
received in this process some pollen of its own flower) pollen from 
freshly opened flowers of another plant, and I then marked my 
flowers with a spot of ink upon the calyx. The rest of the flowers 
I kept in my room, untouched and protected from insects. All the 
flowers were perfectly fertile. On May 21 the twenty nutlets of 
the five flowers which I had fertilised on April 27 had all fallen 
out, and I succeeded in finding them all. On June 8 I collected 
on the surface of the pot seventy-eight nutlets which had fallen 
from the self-fertilised flowers. Lamiwm purpureum is, there- 
} fore, certainly homogamous, and in default of insect-visits fertilises 
) itself regularly. 
Visitors: A. Hymenoptera—Apidw: (1) Apis mellifica, L. § (6); (2) 
Anthophora pilipes, F. 9 § (19—21); (3) Bombus hortorum, L. ? (21); (4) 
_ B. pratorum, L. 2 (114) ; (5) B. agrorum, F. 9 (12—15) ; (6) Melecta armata, 
Pz. 2 (124), all sucking in the normal way, and sometimes brushing off the 
pollen from their heads into their collecting-baskets ; (7) Halictus sexnotatus, 
_K. 9 (4); (8) H. cylindricus, K. 2 (3); (9) H. leucopus, K. 92; these three 
_ try in vain to reach the honey, and abandon the plant after a few attempts. B. 
Diptera—Bombylide : (10) Bombylius major, L. (10), s. See also No. 590, m1. 
K K 
