P. RT III. | THE MECHANISMS OF FLOWERS. 405 
|G. campestris, L., and G. obtusifolia, Willd., are adapted for fertili- 
1 sation by humble-bees and Lepidoptera in the same way as 
G. Amarelia, L. (No. 570, vol. xv.; No. 609, figs. 133-135). 
4 
bb 
A 
h 
Hil 
D 
Fic 135.—Gentiana campestris, L. 
A.—An old flower. The calyx and nearly half of the corolla have been removed. 
_ 8B.—Essential organs from a flower in the act of opening. The stigma is mature, the anth¢ 
@ still closed ; but they dehisced while I was drawing them (B’). 
C,—Upper part of the pistil and of two opposite stamens, in their natural position: from a 
somewhat older flower. 
um Sm whose branches have closed up after being dusted with pollen (x 7). (Madulein 
: @ un e ; 1879. 
H.-A flower viewed directly from above (natural size). 
had part of the pistil and of two stamens in their natural position: from still older 
wer (xX 7). 
(Albula, August 20, 1878). 
ay 
to 
> 
¢ . obtusifolia is proterandrous, G. tenella and G. nana homo- 
gamous, G. campestris sometimes homogamous, sometimes slightly 
_ proterogynous. 
ye 
REVIEW OF THE GENUS GENTIANA. 
_ A comparison of the very numerous Alpine Gentians suggests 
the following theory of their evolution. 
ia The genus Gentiana splits into two main divisions, in one of 
| which honey is secreted by the base of the ovary, in the other by 
| _ the base of the corolla. 
| We have an offshoot of the first main division in G. lutea, 
_ which stands on a much lower grade than the other species and 
hearer to the primitive form. The ancestors of the genus un- 
| doubtedly had, like G. Jutem, fully open flowers with almost free 
