004 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Self-fertilization and Cleistogamy in Orchids.*— Mr. 11. N. Kidley 

 points out four common methods of self-fertilization among orchids : — 

 (1) By breaking up of the pollen-mass and the falling of the pollen, 

 either directly upon the stigma or into the labellnm, whence it comes 

 into contact with the stigma. This, of course, can only ha])pen in the 

 case of orchids with pulverulent pollen. (2) By tlio falling of the 

 pollen-masses as a whole from the clinandriuni into tlie stigma. This is 

 probably not rare, but the author has met with records of but few 

 examples. (3) By the falling forward of the pollinia from the clinan- 

 driuni or the anther-cap, the caudiclc and gland remaining attached to 

 the column. (4) By flooding of the stigma. The pollen-masses remain 

 in the anther-cap or on the clinandriuni, while the stigma exudes so 

 great a quantity of stigmatic fluid that it eventually reaches the edge of 

 the pollinia, which immediately emit pollen-tubes. This seems to be 

 the commonest method of self-fertilization. 



Self-pollination of Spergnlaria salina.f — While this species from 

 Egypt and the oases of the Libyan desert is described as having open 

 flowers with pink petals, Herr P. Magnus finds it at Kissingen cleisto- 

 gamous and usually with only three stamens. The apetalous condition 

 and reduction in the number of stamens he believes to be a hereditary 

 peculiarity in certain localities due to the continued absence of any 

 means of pollination. 



Fertilization of Cattleya labiata.|— Mr. H. J. Veitch deduces the 

 following general statements from a series of observations he has made 

 on the fertilization of Cattleya lahiata : — The impregnation of the ovules 

 of Cattleya lahiata var. Mossise, under glass in the climate of London, 

 takes place from 75-90 days after the pollination of the flower, the 

 lenfTth of time being doubtless influenced by the state of the weather 

 durino the interval, and especially by the amount of direct sunlight the 

 plants receive ; the more direct sunlight, the shorter the interval, and 

 vice versa. A proportion of the ovules only are fertilized ; but how 

 great that proportion is it is not possible to determine with certainty ; it 

 is never probably much less than one-half; it probably varies from a 

 little leFS to a little more than one-half. It is certain also that of the 

 seeds which are mature and good, a greater or less proportion of them 

 failed to germinate under artificial conditions. It takes about twelve 

 months, under the same conditions, to efifect the maturation of the 

 capsules ; it being highly probable that during the winter months, when 

 the temperature in which the plants are kept is comparatively low, and 

 the amount of direct sunlight and suuheat is at the minimum, there is 

 a cessation of growth which is renewed as the summer months are 

 approached. 



C2) Nutrition and Growth (including Movements of Fluids). 



Daily Assimilation of Carbohydrates. § — From the results of a 

 number of experiments on the chemical composition of leaves in the 



♦ Journ. Linn. Soc (Bot.), xsiv. (188S) pp. 3S9 94 (1 pi.). 



t SB. Gcsull. Xaturf. Freunde Berlin, Feb. 28, 1888. See Bot. Centralbl., xxxv. 

 (1888) p. 5. 



+ Journ. Linn. Soc. (Bot.), xxiv. (1888) pp. 395-406 (14 figs.). 



§ 'Zur Kenntuisdd. tagl. Assimilation clcr Kolilehydrate,' Ilalle, 1887. See Bot.' 

 Ztg., xlvi. (1888) p. 4G5. 



