196 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
that the same individual plant (in Origanum vulgare ) may be either 
female or hermaphrodite, according to its external conditions. The 
proximate cause of one flower being female and another hermaphrodite 
appears to be some difference in nutrition. The phenomena vary greatly 
with the nature of the soil and climate, with the season of the year, and 
other conditions. But, while greatly dependent on external causes, they 
may also be to a large extent fixed by natural selection and heredity. 
Androdioecism, which is very rare, is certainly due to lack of nourish- 
ment. The author regards dicecism, in Angiosperms, as descended from 
hermaphroditism. Cleistogamy is also a very variable phenomenon, 
appearing sporadically in many plants, constantly in others. It varies 
with the time of year, soil, climate, and temperature. 
Flowers of Ruppia.* * * § — M. E. Roze describes the structure of the 
flowers and the mode of pollination of the flowers of Ruppia maritima 
and rostellata , the two species agreeing with one another in all important 
points except the number of ovaries. The pollen-grains have a double 
coat ; at first nearly spherical, they become three-lobed when mature. 
The stigma has a longitudinal crevice furnished with a certain number 
of papillose cells. When the spadix, which consists of both male and 
female flowers, emerges from its spathe, the anthers usually become 
detached, and rise to the surface of the water, which becomes covered 
with pollen. But in other cases the anthers do not become detached, 
and then they open in the ordinary way in the air. Ruppia appears, 
therefore, to present a transitional mode of pollination, between aerial 
and aquatic. 
Abnormal Willow-catkins.f — Herr J. Haring has observed numerous 
examples of Salix caprea and S. cinerea , in which the male catkins have 
assumed a more or less completely pistilliferous, and the female catkins 
a more or less completely staminiferous character. 
Cross-pollination and Self-pollination. — Herr E. Loew f has col- 
lected the results of a very large number of observations with regard to 
the pollination of the native plants of Central and Northern Europe, 
and of Greenland. The contrivances for autogamous pollination are 
more numerous in the higher than in the lower alpine region, and this 
increase is most strongly exhibited in the high alps of Norway, and in 
the arctic flora of Greenland. The arctic flora of Greenland, Nova 
Zembla, and Spitzbergen also includes a very large proportion of 
species with exposed or only partially concealed honey. Anemophilous 
species are also more numerous, as contrasted with entomophilous, in 
the most northerly latitudes. 
Mr. M. S. Evans § describes the mode of pollination in two South 
African species of LorantJius , L. Kraussianus and Dregei. In the former 
species the pollen is violently scattered by the sudden release of the 
anthers from the corolla-tube ; but the pollen does not in this way reach 
the stigma ; this is pollinated exclusively by a sun-bird ( Cinnyris oli- 
* Bull. Soc. Bot. France, lxi. (1894) pp. 466-80 (1 pi.). 
f Oesterr. Bot. Zeitschr., xliv. (1894) pp. 386-7, 415-8. 
t Bliitenbiol. Flor. d. mittler. u. nordl. Europa u.s.w., Stuttgart, 1894, viii. and 
424 pp. See Bot. Centralbl., lx. (1894) p. 303. 
§ Nature, li. (1895) pp. 235-6. 
