164 
H. N. Ridley. 
difficult problem. It should also be recalled in this relation that 
Gilson obtained cellulose in a crystalline form, that Arthur Meyer 
has advocated the crystalline nature of starch-grains, and that 
Ambronn explained the optical properties of cork by a reference to 
the crystalline constitution of cuticularised and suberised 
RUDOLF BEER. 
membranes. 
INSECT-ATTRACTIONS IN FLOWERS. 
N an article entitled “ What part does colour play in the 
attraction of insects to flowers” published by Mr. Tansley in 
the New Phytologist (Vol. III., No. 2, p. 51), the author discusses 
this question apropos of the experiments of Plateau and Andreae. 
The papers of these naturalists I have not seen, but I think that 
perhaps a few notes of observations made in the tropics may be of 
some interest and perhaps throw light on the question. 
“ Andreae concludes,” says Mr. Tansley, “ that of the day-flying 
insects, the biologically higher types, i.e. those with a relatively long 
life in the winged state, and with a long direct flight, are characterised 
by sharp sight and are attracted to flowers mainly by their colour, 
while the biologically lower forms, i.e. those with a short life in the 
winged condition and a short flight, have less power of sight and 
are more dependent on smell” (p. 54). I should venture to traverse 
this as too general a statement. Insects are so varied in their 
habits, in the tropics at least, that those of the same group may be 
apparently attracted either by scent or colour according to circum¬ 
stances, or rather according to the habits of the species. Thus for 
example the great blue-black butterfly, Papilio Esperi dashes about in 
the mid-day sun along jungle paths and only stops at red flowers 
most of which are quite scentless at that time, at least to an 
ordinary observer. If a piece of red paper or cloth, or a fallen 
Hibiscus flower lies in its track it will often stoop at it and inspect 
it, clearly showing that it is attracted by colour only. The other 
Papilios such as P. Sarpedon dash about in a similar way, but are 
chiefly attracted by the white-flowered Eugenias, the red or orange 
Lantana and other more distinctly scented plants. 
Amathusia Phidippus , as well as the Thaumantidae, only leave 
the dark recesses of the jungle at dusk, when brightly coloured 
flowers are practically invisible, and consequently do not attract 
