68 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
same journey. It is, however, possible to obtain hybrids between the 
two species, and then the standard is always white, and all the 
remainder of the corolla yellow. 
A possible case of parthenogenesis in Bryonia dioica is recorded. 
Fertilization of Caryophyllaceae.* * * § — Prof. E. Warming describes 
the structure of the flowers of a large number of Scandinavian and 
Arctic Caryophyllaceae, especially in relation to the mode of pollination. 
Honey was found in all the species examined. The flowers are 
usually proterandrous ; the stamens borne on the sepals are developed 
first, then those borne on the petals, and finally the stigmas ; proterogyny 
occurs in a few species, and is apparently correlated with the reduction 
of the petals. The author confirms the observation of Muller that the 
degree of proterandry is in proportion to the size of the flower ; but 
the arctic species, even when large-flowered, are more inclined to 
homogamy than those from lower latitudes. Self-pollination is frequent, 
and results in perfect fructification ; anemophily is very rare, but occurs 
in Silene Otites. Many homogamous species are pleogamous, and these 
are generally gynodioecious ; this the author regards as not advantageous, 
but rather as a degeneration, caused by external or internal conditions. 
The larger flowers are usually hermaphrodite, while the smaller flowers 
are more or less reduced. Cleistogamous flowers are not uncommon. 
In many species the flowers remain closed in dark and cold weather, and 
are then self-fertilized. He does not find that the female are more 
fertile than the hermaphrodite flowers. 
Fertilization of Aracese.f — Prof. G. Arcangeli describes the pheno- 
mena connected with the opening of the inflorescence of Helicodiceros 
muscivorus (Araceae). The first day of the expansion of the spathe, he 
found imprisoned within it as many as 378 insects, of which 371 were 
Diptera, and 7 Coleoptera. From the entire absence of any digestive 
glands on the inner surface of the spathe, or any other organs for the 
absorption of nutritive material, he rejects Schnetzler’s explanation that 
the dead bodies of the insects serve for the nutrition of the plant, and 
believes that they assist in the process of pollination. 
Returning to the fertilization of Dracunculus, Prof. Arcangeli | adduces 
additional facts in favour of his view that the flowers of D. vulgaris are 
pollinated chiefly by necro-coleoptera. He was able to effect impregna- 
tion by the artificial introduction into the inflorescence of specimens of 
Saprinus and Dermestes which had already been pollinated. 
Artificial Germination of Milk-weed Pollen.§— Prof. B. D. Halsted 
has been able to germinate the pollen-grains which constitute the 
pollinia of Acerates viridiflorum (Asclepiadeae) by immersing them in 
agar, and was able to watch the very beautiful movements of protoplasm 
within the pollen-grain after it has put out its tube. These consist 
of a continuous current round the large vacuoles. The same phenomenon 
w r as observed in various species of Asclepias. 
* Bot. Foren. F< stskr. (Copenhagen), pp. 194-296 (29 figs.), 
t Nuov. Giorn. Bot. Ital., xxii. (1890) pp. 467-72. 
j Malpighia, iv. (1890) pp. 254-61. Cf. this Journal, 1890, p. 629. 
§ The Microscope (Trenton, N. J.), x. (1890) pp. 229-31 (4 figs.). 
