142 THE FERTILISATION OF FLOWERS. [PART III. 
them increase the chance of cross-fertilisation ; rendering it likely 
in spite of the great number of anthers, that an insect on alighting 
will touch a stigma first, though self-fertilisation is also very 
probable. In all, self-fertilisation occurs in default of insect- 
visits, and is without doubt the usual mode of reproduction in 
the less conspicuous forms. : 
Cratoxylon formosum has dimorphic flowers (167, 213). 
Orv. MARCGRAVIACE LZ. 
In this order bracts secrete honey and make the flower 
conspicuous by their bright colours. They have accordingly 
the most various forms (spurs, spathes, etc.), and are of as much 
importance to the plant as petals usually are. Delpino bases a 
new subdivision of the order upon the modifications of the bracts. — 
The flowers are proterandrous. 
In Marcgravia nepenthoides there occurs beneath a wreath of 
pendulous flowers a group of honey-secreting cups. They attract 
insects, which in turn attract insectivorous birds, and these, while — 
feeding on the insects sitting upon the nectar-cups, touch and — 
cross-fertilise the flowers above (56). 
An interesting paper on Marcgraviacez and their Nectaries, 
with fine figures, was contributed by Ludwig Wittmack to 
Kosmos, vol. v., 1879 (784.) 
Orv. MALVACE LZ. 
MALVA SILVEsTRIS, L., and M. rotrunpirot1A, L.—These © 
species often occur together, and flower side by side for months ~ 
at atime. In the struggle for existence, IZ. rotwndifolia has the 
advantage in being content with poorer soil, in the appearance of 
its flowers from one to several weeks earlier, and in the possibility 
of regular self-fertilisation; JZ silvestris, on the other hand, in~ 
its more vigorous growth, and much greater attractions for ~ 
insects. These advantages seem to balance one another, for, — 
about Lippstadt at least, both species grow together in equal 
abundance, 
In both species, a pyramidal group of anthers occupies the 
middle of the young flower, and surrounds the stigmas which are 
still unripe and folded together; later on, the stigmas become 
exserted and radiate outwards. Honey is secreted in five pits 
between the bases of the petals, and protected by hairs, and insects 
