66 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
grains, even when large and brightly coloured, frequently pollinate the 
stigma before any insect, not excepting Thrips, can possibly enter the 
flower. Special examples of self-pollination are given in Lepachys 
pinnata and Bidens frondosa ; in the latter species we have an arrange- 
ment by which the visits of insects are prohibited. 
Other examples of habitual self-pollination are given in Symplocarpus 
fvetidus (Aroideae), in which the flowers are frequently proterandrous, and 
as frequently proterogynous, Portulaca pilosa, the flowers of which open 
only in the suushine, and yet seed abundantly when grown in the shade, 
Cuphea Zimpani (Lythraceae), and Lopezia coronata (Onagracese). Daphne 
Cneorum, on the other hand, of which the flowers seem well-arranged for 
self-fertilization, never produces seed. 
Pollination of Insular Floras.* * * § — From an investigation of the flora 
of the island of Norderney, belonging to North Friesland, Herr C. 
Verhaeff agrees in the conclusions of Behrens that, in general, insular 
floras contain a larger proportion of anemophilous species than con- 
tinental ; and that the number of winged insects being also reduced, the 
pollination of the flowers is facilitated by their brighter colour. A list 
is appended of a number of the insular species with their insect-visitors. 
Herr R. Alfken f has investigated, with the same object, the flora of 
the island Juist in the Baltic. He dissents from the statement of 
Behrens that the number of insects inhabiting islands is small, and gives 
a list of 597 species found on Juist. 
Flowers and Insects.^ — Mr. C. Robertson publishes the instalment 
of his series of papers on the pollination of flowers and insects relating 
to the Asclepiadese, Gentianacese, Polemoniaceae, Hydrophyllacete, Con- 
volvulaceae, Borragineae, Solanaceae, and Scrophulariacese. 
Fertilization of Araceae.§ — Sig. U. Caleri describes the structure of 
the inflorescence and spathe of Arum, Dioscoridis, which form an ad- 
mirable contrivance for the capture and temporary incarceration of 
diptera ; these insects being the chief, though possibly not the sole, 
agent in the pollination of the female flowers. 
Reverting to the mode of pollination of Helicodiceros muscivorus, 
Prof. G. Arcangeli [| gives a lengthy list of diptera and coleoptera found 
within the spathe. 
Pollination of Armeria maritima.l — Dr. P. Knuth describes the mode 
in which the flowers of the common thrift are pollinated, which may 
be either by self-pollination or cross-pollination. They are visited by 
several species of Hymenoptera, Diptera and Lepidoptera, a list of 
which is given. 
* Abhandl. Naturwiss. Vereins Bremen, xii. (1891) pp. 65-88. See Bot. Cen- 
tralbl., xlviii. (1891) p. 46. 
t Tom. cit., pp. S7-130. See Bot. Centralbl., xlviii. (1891) p. 46. 
x Trans. St. Louis Acad. Sci., v. pp. 569-98. See Bot. Centralbl., xlviii. (1891) 
p. 188. Cf. this Journal, 1891, p. 769. 
§ Nuov. Giorn. Bot. Ital., xxiii. (1891) pp. 583-8. Cf. this Journal, 1891, p. 68. 
|| Tom. cit., pp. 588-95. 
Bot. Centralbl., xlviii. (1891) pp. 41-3 (2 figs.). 
