PART III.] THE MECHANISMS OF FLOWERS. 133 
surfaces, which are covered with long papille, upwards. An insect 
visiting a young flower dusts itself with pollen, and also applies 
pollen from the same or from another flower to the tips of the 
stigmas; in an older flower it is likely to dust the outspread 
_ stigmas with pollen from another flower ; in the absence of insects 
the stigmas as they curve outwards come in contact with the 
anthers still covered with pollen. 
Visitors: A. Diptera—(a) Syrphidw: (1) Rhingia rostrata, L., s. (May 
_ 10, 1870); (b) Muscide: (2) Pollenia vespillo, F. ; (3) P. rudis, F., both 
_ s, and inserting the proboscis three to five times in each flower (April 17, 1871). 
_ B. Hymenoptera—Apide : (4) Apis mellifica, L. $,—I saw (April 3, 1871) 
the honey-bee in great numbers flying over a bare field of C. semidecandrum, 
sucking the tiny flowers by dipping its proboscis once into each. 
Cerastium viscosum, L., has cleistogamic flowers (40). > 
63. MALACHIUM AQUATICUM, Fries.—The flowers of this plant 
are more conspicuous than those of Cerastiwm triviale and C. semt- 
decandrum, but less so than those of C. arvense and Stellaria 
Holostea ; in the same intermediate position stands the amount of 
its insect-visits and its floral arrangement, which favours both cross- 
and self-fertilisation. The flower is proterandrous, and in absence 
of insects the ends of its outspread stigmas come in contact with 
the pollen-covered anthers. The styles vary in number from three 
to five, the latter number being most frequent, so that Malachiwm 
here probably resembles the common ancestors of Cerastiwm and 
Stellaria. 
Visitors : A. Diptera—(a) Syrphide: (1) Helophilus lineatus, F. ; (2) Eristalis 
 arbustorum, L. ; (3) Syritta pipiens, L. ; (4) Ascia podagrica, F., all ab., s. ; 
| (b) Muscide : (5) Anthomyia sp., s. B. Coleoptera—Nitidulide : (6) Meli- 
gethes, ab., Lh. OC. Thysanoptera: (7) Thrips, very freq. D. Hymenoptera 
| —Apide: (8) Prosopis communis, Nyl. 9, s. ; (9) Pr. hyalinata, Sm. 2, s. ; 
(10) Halictus sexnotatus, K. ¢, s. 
64. STELLARIA GRAMINEA, L.—The nectaries surround the bases 
of the five outer stamens as green, fleshy swellings. The flowers © 
exhibit three stages, which, however, merge one into another. In 
the first period, the five outer stamens curve in towards the middle 
of the flower, and their anthers dehisce widely, covering them- 
‘selves all round with pollen; the inner stamens are meanwhile 
bent outwards, and their anthers are still closed. The styles are 
not yet fully developed, and are curved inwards with their papillar 
surfaces directed downwards. ‘The five inner stamens dehisce 
before the other five have withered, but still remain bent farther 
outwards; this marks the second stage. As these inner stamens 
