386 THE FERTILISATION OF FLOWERS. [PART II. 
are alladapted for Lepidoptera by their colour and by the narrowin, 
of the mouth of the tube. 4 
All these species, with the exception of P. longiflora, are helena 
styled (609). : 
Primula farinosa occurs both on the Alps and in North 
Germany, and probably owes this wide distribution to the mild 
climate succeeding the Glacial period. On the Alps, where it is 
visited by Lepidoptera in great numbers (I have noted forty-eight 
species), the entrance of the flower is distinctly narrower than in - 
North Germany, where Lepidoptera are less plentiful and where 
the plant has probably to depend on the visits of bees (609). 
Primula longiflora is homostylic, and adapted by its long narrow 
tube for Lepidoptera. The tube is 16 to 24 mm. long, and the 
honey is, therefore, accessible only to Macroglossa stellatarum (25 to 
28) and to Deilephila euphorbie (25 mm.) pics t 3 all the Alpine 
Lepidoptera. 
289. Horrontia PALUSTRIS, L.—The flowers are dimorphic. 
Honey is secreted by the ovary. In both kinds of flowers, the tube 
NIB NS 
Fic. 127.— Hottonia palustris, Vu. 
1.—Long-styled flower. 
2.—Its stigmatic panies: 
8.—Short-styled flower 
4.—Its stigmatic papille, on the same scale-as 2. 
is 4 to 5 mm. long, the organs of one sex standing in its entrance — 
and those of the other projecting 8 to 4 mm. beyond. In the — 
damp state the pollen-grains of the long-styled form (which i 
legitimate crossing have to traverse a style 4 to 5 mm. long) are — 
spherules ‘011 to ‘014 mm. in diameter; those of the hoe ee 
