782 SUMMARY OF CURRENT RESEARCHES RELATING TO 



p. Physiology,* 

 (1) Eeproduction and Germination. 



Fertilization of Epipactis latifolia.f — Mr. A. D. Webster states that 

 all or nearly all his observations tend to show (1) that Epipactis latifolia 

 is very imperfectly fertilized ; (2) that, although visited by insects, cross- 

 fertilization seldom takes place ; and (3) that self-fertilization by the 

 pollen falling spontaneously on the stigma is not uncommon. 



That the plant is very imperfectly fertilized is evident from the small 

 quantity of seed produced. Nineteen plants grovping in consecutive order 

 in one wood were examined, and out of a possible 492 capsules only 38 

 produced seed. That, although visited by insects, cross-fertilization seldom 

 takes place, is proved by the following observations. Amongst insects of 

 sufficient size to remove the pollinia that have been seen visiting the jfiowers 

 of this Epipactis, may be mentioned the red-tailed humble bee and our 

 common wasp, the latter, however, but very rarely. The autlior has 

 observed the above-mentioned bee enter several flowers on two different 

 plants without in any case removing the pollinia ; also a red-tailed humble 

 bee visiting sixteen flowers on a spike without removing any of the pollinia. 



Self-fertilization by the pollen falling spontaneously on the stigma is 

 not uncommon. The author has observed that the pollen-masses in a few 

 days, or perhaps a week, after the flowers open, become swollen, or the 

 particles of pollen disunited so as to protrude slightly beyond the sharp 

 upper edge of the stigma. The pollen becomes friable, and before the 

 plant withers, either spontaneously or by the action of the wind, falls on 

 the stigma and other parts of the flower. 



Influence of Ozone on Germination.^ — Herr A. Vogel states that 

 strongly ozonized air seems to have no harmful influence on the germina- 

 tion of seeds. Milk and meat can be kept for a longer time in ozonized 

 air without change than in ordinary air. 



(S) Nutrition and Growth. 



Transpiration and Assimilation in Leaves treated with Milk of 

 Lime.§ — In view of the mode of treatment of vines for the destruction of 

 the Peronospora, the question is of some importance whether the functions 

 of transpiration and assimilation are checked or prevented by the applica- 

 tion to the leaves of milk of lime. From a series of experiments on the 

 leaves of the horse-chestnut, cherry, and vine, Dr. G. Cuboni has come to 

 the conclusion that it has no injurious effect. 



(3) Movement. 



Part taken by the Medullary Eays in the Movement of Water.H — 

 Dr. J. M. Janse has confirmed by experiment Godlewski's theory^ that the 

 living parenchymatous elements of wood take an active part in the move- 

 ment of the transpiration-current. The objections made by various authors 

 to the soundness of this hypothesis he regards as unimportant ; and states 

 that experiments show that the part taken by the medullary rays is con- 

 nected with certain conditions : — a definite arrangement of the elements of 

 the wood, greater power of resistance to filtration, and the unilateral action 



* This subdivision contains (1) Eeproduction and Germination; (2) Nutrition and 

 Growth ; (3) Movement ; and (4) Chemical Changes (including Eespiration and 

 Fermentation). t Bot. Gazette, xii. (1887) pp. 104-9. 



J Bied. Centr., 1887, p. 142. See Journ. Chem. Soc. Lend., 1887, Abstr., p. 516. 



§ Malpighia, i. (1887) pp. 295-310 (1 pi.). 



II Pringsheim's Jahrb. f. Wiss. Bot., xviii. (1887) pp. 1-69 (1 pi.). 



il See this Journal, 1886, p. 1016. 



