HARDWICKE'S SCIENCE-GOSSIP. 



123 



grown shortly after the blossoms begin to fade, 

 shrivelling up when the fruit begins to form. Por 

 this reason the experiment can succeed only at that 

 limited period when the flowers are fading. Best 

 adapted for the purpose are those panicles which 

 have done flowering at the base, and still have a 

 few blossoms at the top. The same panicle cannot 

 be lighted twice. The rachis is uninjured by the 

 experiment, being too green to take fire, and be- 

 cause the flame runs along almost as quick as 

 lightning, becoming extinguished at the top, and 

 diffusing a powerful incense-like smell. 



In 1SI3, the luminosity of plants was recorded in 

 the Proceedings of the British Association. Mr. 

 R. Dowden is said to have made mention of a 

 luminous appearance on the double variety of the 

 common Marygold. This circumstance was noticed 

 on the 4th August, 1S42, at S o'clock p.m., after a 

 week of very dry weather. Pour persons observed 

 the phenomenon. By shading off the declining 

 daylight, a gold-coloured lambent light appeared to 

 play from petal to petal of the flowers, so as to make 

 a more or less interrupted corona round its disk. 

 It seemed as if this emanation grew less vivid as 

 the light declined ; it was not examined in darkness. 

 When this subject was discussed, Dr. Allman ex- 

 pressed his opinion that the phenomenon was not 

 at all due to phosphorescence, but was referable to 

 the state of the visual organ, that is, an optical 

 illusion. This led Mr. Babington to mention that 

 he had seen, in the south of England, a peculiar 

 bright appearance produced by the presence of the 

 Schistostega pennata, a little moss, which inhabited 

 caverns and dark places ; but this, too, was objected 

 to by a member present, who stated that Professor 

 Lloyd had examined the Schistostega, and had found 

 that the peculiar luminous appearance of that moss 

 arose from the presence of small crystals in its 

 structure, which reflected the smallest portion of 

 the rays of light. 



These remarks having been published iu the 

 Gardener's Chronicle* Dr. Edwin Lankester in a 

 succeeding number communicated some observa- 

 tions on the subject of luminosity, in plauts more 

 especially,! in which he referred to many of the 

 facts of luminosity which had been recorded. 



" The light from the moss," he says, " mentioned 

 by Mr. Babington has also been observed in Ger- 

 many on another species {Schistostega osmundacea). 

 It has been observed by Punk, Brandeuberg, Nees 

 von Esenbeck, Hornschuh, and Struve. Bridel- 

 Brideri and Agardh attributed this light to a small 

 alga, which the former called Catoptridium smarag- 

 dinum, and the latter Protococcus smaragdinus,-which 

 they supposed occupied the moss. Unger, how- 

 ever, has examined the moss accurately, and finds 



* Gardener's Chronicle, 1843, p. 691. 

 t Ibid., 1843, p. 710. 



that at certain seasons the peculiar utricles of this 

 moss assume a globular form, and being partially 

 transparent, the light is refracted and reflected in 

 such a way as to present a luminosity on the sur- 

 face of the vesicles. Meyen says he has confirmed 

 Unger's observations." 



With regard to the light given out from flowers, 

 the doctor cites Christina Linne, Linnaeus, the 

 younger Linnoeus, Haggren, Crome, Zawadzki, 

 Hagen, Johnson, and the Duke of Buckingham, as 

 amongst the observers whose experiences have been 

 recorded. The plants enumerated by him are the 

 Nasturtium {Tropceohm majus), the Sunflower 

 Eelianthus animus), the Marygold {Calendula offici- 

 nalis), African Marygold {Tagetes erecta and Tagetes 

 patula), Martagon Lily {Lilium chalcedonicum and 

 Lilium bulbiferum), the Tuberose {Polyanthus tube- 

 rosa), Poppy {Papaver orientate) Chrysanthemum 

 {Chrysanthemum inodorum), Evening Primrose 

 {(Enothera macrocarpa), and Gorteria rigens. 



In addition to the observations on the light of 

 flowers, there are some on the phosphorescence 

 and luminosity of sap. Mornay describes a tree in 

 South America, called Cipo de Cunaman, with a 

 milky juice, which gave out in the dark a bright 

 light. Martius, also, in a plant which he named 

 Et'phorbia phosphorea, says that, when wounded, the 

 sap gave out a light. To these instances is added 

 a reference to Senebier, who observed in his experi- 

 ments on arums, on one occasion, when confining 

 an arum in oxygen gas, that it gave out light as 

 well as heat. 



On the same page of the Gardener's Chronicle on 

 which Dr. Lankester's observations are printed, 

 another correspondent expresses surprise that any 

 doubt should be thrown on the luminosity of plants. 

 "Por,"he says, "I have observed it frequently, and 

 have looked for it on each succeeding summer, on 

 the Double Marygold, and more especially the 

 Hairy Bed Poppy {Papaver pilosum), iu my garden 

 at Moseley, in Worcestershire. In the evening, 

 after a hot dry day, the flashes of light afforded 

 much amusement to myself and to others." 



Fifteen years later, and the subject was again re- 

 vived in the pages of the Gardener's Chronicle, by 

 the record of certain experiences tending to corro- 

 borate those of others which had previously been 

 made, and to which we have already directed the 

 attention of our readers. 



This observer, quoting from his diary, states :— 

 " We witnessed (June 10th, 185S) this evening, a 

 little before nine o'clock, a very curious pheno- 

 menon. There are three scarlet verbenas, each 

 about nine inches high, and about a foot apart, 

 planted in the border in front of the greenhouse. 

 As I was standing a few yards from them, and look- 

 ing at them, my attention was arrested by faint 

 flashes of light passing backwards and forwards 

 from one plant to the other. I immediately called 



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