102 THE FERTILISATION OF FLOWERS. [PART III. 
must touch simultaneously the stigma and the pollen-covered faces 
of three anthers, one short and two long. If, in continued bad 
weather, the flowers do not open fully, self-fertilisation is effected 
by the longer anthers, as in JV. silvestre (590, 1., 609). 
28. ARMORACIA AMPHIBIA, Koch. (Nasturtium amphibium, BR. 
Br.).—The structure of the flower resembles that of Nasturtiwm 
silvestre. 
Visitors : A. Hymenoptera— Tenthredinide : (1) Tenthredo notha, K1., very 
abundant, passing from flower to flower and dipping its proboscis down to 
suck,—head and thorax richly dusted with pollen. B. Diptera—(a) Empide : 
(2) Empis livida, L., s. ; (6) Syrphide : (3) Rhingia rostrata, L., s. ; (4) Syritta 
pipiens, L., s.; (5) Eristalis arbustorum, L., s. 
Arabis alpina, L., is homogamous (609). 
Arabis bellidifolia, Jacq., is proterogynous, with long-lived 
stigmas (609). 
29. ARABIS HIRSUTA, R. Br.—The arrangement of the flowers 
differs from that of Nasturtium silvestre in that only two glands 
lying internal to the base of the shorter stamens secrete honey, and 
that in most flowers the longer stamens arch over the stigma, and 
shed their pollen on it, if it is not removed by insect visitors. 
Flowers also occur in which the anthers of the longer stamens stand 
on the same level as the stigma, and shed their pollen in immediate 
contact with it. 
Visitors : A. Hymenoptera—(a) Sphegide : (1) Ammophila sabulosa, L., s. ; 
(b) Apide: (2) Apis mellifica, L. $,s.; (3) Halictus sexnotatus, K. 9, ep. ; 
(4) Andrena albicrus, K. ¢,s. 3B. Lepidoptera—Bombyces : (5) Euprepia 
Jacobee, L.,s. C. Diptera—Syrphide : Syritta pipiens, L., s. 
30. CARDAMINE PRATENSIS, L.—This species differs greatly from 
the preceding forms in the situation of its honey, in the position of 
its anthers, in the conspicuousness of its flowers, and hence also in 
the number of its visitors. Two large honey-glands surround the 
bases of the two shorter stamens as green fleshy cushions which are 
most marked at the outside and secrete their honey at that point : 
two smaller honey-glands occupy the position of the two aborted 
smaller stamens," 7.¢. they are placed antero-posteriorly, between the 
1 Kichler’s view of the floral symmetry and number of the parts in Crucifere is 
different from that advanced here by the author, and is now more generally adopted. 
He regards the number two as the basis of the floral whorls, and looks upon the four 
petals and the four inner stamens as due to the chorisis respectively of two antero- 
posterior petals and stamens. On this view the whorls alternate regularly with each 
other, and the flower is symmetrical. (Eichler, Blithendiagramme, vol. ii.) 
