210 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
tion of Yucca filamentosa by Pronuba Yuccasella , and of other species of 
Yucca by other members of the same genus of moths. Self-pollination 
is exceedingly difficult, and all the species of Yucca belong to that class 
of plants in which fertilization is dependent on the visits of a single 
species of insect. The adaptations for this purpose in the structure of 
both flower and insect are described in detail. The female pierces the 
ovary, and deposits its eggs between the ovules, after which it removes 
a quantity of pollen from the anthers, and stuffs it into the stigmatic 
cavity. In this way ten or twelve eggs are deposited, and a correspond- 
ing number of ovules destroyed ; but, as the number of ovules in the 
ovary is very large, this does not appreciably affect the fertility of 
the plant. Yucca filamentosa appears to be absolutely dependent on the 
visits of Pronuba Yuccasella for the production of seeds ; it also visits 
Y. angustifolia ; while Y. Whipplei is pollinated by P. maculata , and 
Y. aloifolia by P. synthetica. 
Pollination in the Juncacese.* * * § — Herr F. Buchenau has investigated 
the mode of pollination in a large number of the Juncaceae, chiefly 
belonging to the genera Juncus and Luzula. Excluding the South 
American genera Disticliia, Patosia, and Oxychloe, which are dioecious, 
all Juncaceae are pro terogy nous. The greater number of the species are 
cross-pollinated and anemophilous, but some are self-pollinated, and a 
few are entomophilous. The flowers of Juncus homalocaulis are entirely 
cleistogamous, and cleistogamy occurs also frequently in a few other 
species of Juncus and of Luzula , especially in J. bufonius. In this 
species it is usually the terminal flowers of the inflorescence that are 
cleistogamous, and these have generally three stamens instead of six. 
The pollen-tubes germinate while still within the anther-lobes, reach 
the nearest stigma, and fix this firmly to the anther. 
Fertilization of the Fig-f — Prof. C. V. Riley enumerates fourteen 
insects as associated with the caprification of the wild figs of North 
America. He recommends the importation for this purpose of Blasto- 
phaga psenes to the fig-growers of California. 
Pollination of Cyclamen persicum.J — Herr P. Ascherson describes 
the mode of pollination of Cyclamen persicum , which corresponds in 
essential points with that of C. europseum. The odour and the very 
marked proterandry point to cross-pollination as the ordinary mode. 
But there are, nevertheless, mechanical contrivances by which self- 
pollination is ensured, failing the visits of insects. A remarkable 
peculiarity of this species is that it possesses two odours, one belonging 
to the corolla, as in C. europseum and allied species, the other to the 
anthers/ He further describes the mode in which the curvature of the 
flower-stalk assists in the pollination of the stigma. 
Parasitic Castration of Lychnis and Muscari.§— M. A Magnin 
confirms, by fresh observations, his previous statement that the pheno- 
mena of the castration of Lychnis diurna by TJstilago antherarum, and of 
* Jahrb. f. Wiss. Bot. (Pringsheim), xxiv. (1892) pp. 363-424 (2 pis. and 1 fig.). 
f Bot. Gazette, xvii. (1892) p. 281. 
X Bor. Deutsch. Bot. Gesell., x. (1892) pp. 226-35, 314-8 (8 figs.). 
§ Comptes liendus, cxv. (1892) pp. 675-8. Cf. this Journal, 1892, p. 387. 
