382 SUMMARY OF. CURRENT RESEARCHES RELATING 1 



the living matter are of very unstable character, liable to numerous re- 

 actions or transformations, so that somechanges may be regarded as loss 

 of character due to the effect of the reagent, while such changes as new 

 incisions in the corolla, etc., are increased differentiations. 5. The 

 changes induced by direct physico-chemical action. 6. Accurate results 

 can only he obtained by the method of injection by studying the course 

 of diffusion of the reagent, time and method of pollination, rate of ex- 

 tension and course of the pollen-tube, and the general structure of the 

 ovule. 7. The germ-plasm of plants appears to have two distinct 

 phases : the one phase in which the meristem splits off into permanent 

 tissues, capable of considerable change by environic forces, but not 

 affecting future generations ; and the second phase, during which the 

 chromosomes are reduced and sexual cells are produced, capable of pro- 

 found change affecting the future of the race. 



General. 



" Elizabeth-Linnaeus Phenomenon." * — F. A. W. Thomas publishes 

 a paper dealing with and explaining " flower-lightning." The author 

 distinguishes between real phenomena due to electrical conditions, and 

 appearances resting solely upon subjective causes. He considers that 

 the so-called " flower lightning," first observed by Elizabeth Linnaeus, 

 daughter of the great Swedish botanist, and afterwards described by 

 Goethe and others, must be regarded as belonging to the latter class ; it 

 is only perceptible in twilight, and appears to be entirely due to optical 

 illusion. The structure of the outer part of the retina renders it 

 sensitive to different intensities of light, but not to colour ; the fovea, 

 i.e. the centre of the yellow spot, on the other hand, is the region of 

 keenest perception of colour ; therefore, when in a certain degree of 

 twilight the image of a red flower moves from the peripheral parts of 

 the retina to the fovea, the red colour appears to become more vivid. 

 At the same instant the waves of light approach the length for pro- 

 ducing maximum activity in those parts of the retina specially adapted 

 to darkness, so that a distinct reflection of the background of the flower 

 is perceived, and this combines with the more vivid perception of red 

 to give an impression of lightning. This impression is intensified if the 

 fading light is bluish-green in colour. 



CRYPTOGAMS. 



Pteridophyta. 

 (By A. Gepp, M.A., F.L.S.) 



Branching in the Ophioglossaceas.t— L. C. Petry has investiga 

 the question of branching in the Ophioglossacete. He finds that : — 

 1. Branching of the rhizome of Ophioglossum vulgatum and 0. pendulum 

 is dichotomous ; there are no axillary or adventitious buds on the 



* Das Elisabeth Linne Phenomenon. Jena : G. Fischer. 1914, pp. 1-53 (1 fig.), 

 t Bot. Gaz., lix. (1915) pp. 345-65 (2 pis. and figs.). 



