66 INTRODUCTION 
10. Flowers with adaptation B, but in which the pollen also ts° more or less 
completely concealed (BB). Zygomorphous. Viola, Anthyllis, Trifolium, Lotus, Vicia, 
Linaria, Alectorolophus. 
Verhoeff represents the most important relationships between his ten chief 
stages of adaptation in the following scheme :— 
M PoB 
BG & BR. 
The classification presents no advance upon that of Miiller, for the Zygo- 
morphous Pollen-flowers (Sarothamnus, Genista, Ulex) are such well-marked 
Hymenopterid Flowers, that they cannot possibly be separated from the Nectar- 
flowers of this group (Anthyllis, Trifolium, Lotus, Vicia, &c.). Such separation 
would be like the artificial division of the Papilionaceae into two separate classes 
(XVI and XVII) in the Linnean classification, according as they are monadelphous 
or diadelphous. And it may be added that the term ‘nectar-flowers’ is applicable 
not only to the extremely simple nectar-containing flowers of Salix, but also to 
Verhoeff’s classes A, AG, AB, B, BG, BB. 
Loew (Beob. iiber den Blumenbesuch von Insekten . . . Weit. Beob. iiber den 
Blumenbesuch ... , Beitr. zur bliitenbiolog. Statistik) has arranged the floral 
classes of Hermann Miller (excluding, however, classes D and K1) in the following 
three groups :— 
I, Allotropous Flowers: these are adapted to various kinds of insects 
possessing a short proboscis. To this group belong classes W, Po, A, and AB. 
II. Hemitropous Flowers: these are imperfectly adapted to some definite 
set of insects possessing a proboscis of medium length. To this group belong 
classes B and B’. 
Ill. Eutropous Flowers: these are more or less exclusively adapted to 
a definite set of insects possessing a /ong proboscis. To this group belong 
Bee Flowers, Humble-bee Flowers, and Lepidopterid Flowers. 
Loew distinguishes three groups of insects, the visitors, respectively, of allotro- 
pous, hemitropous, and eutropous flowers. ‘These will be discussed later. 
Taking into account the observations first made (1892) by W. Burck, and 
confirmed (1897) by J. H. Hart, which prove that bats act as pollinating-agents, 
and collating the groupings of Delpino and Miiller, the following classification 
of plants, according to their flower pollination, may be advanced’ :— 
1 Kerner (‘Die Schutzmittel des Pollens,’ pp. 45, 46, note) employs the term Kangaroo flowers in 
describing the floral arrangements of Dryandra (Proteaceae). The flowers are inserted on the rim 
