DEVELOPMENT OF LIGHT. 543 



On light from the flowers : 

 Kongl. Svenska Wetenscap-Academiens Handlirignr, J762, p. 284. 



(The observations of Linnaeus's daughter on Tropceolum}. 

 Bertholon de St. Lazare, de 1'Electricite des Vegetaux. Paris, 1783, 



p. 335. ( Tropceoitim majus). 

 Kongl. Wetenscap-Academien Nya Hand!., 1778, p. 82. (Helianthus 



annuus, Lilium bulbiferum, Tagetes spec.}. 

 Treviranus, Zeitschr. f. Physiol., vol. iii. pp. 257 269. 

 Hoppe, Botan. Taschenbuch f. d. Jahr 1809, p. 52. (Tropceolum 



majus). 

 Bauragartner and Ettinghausen, Zeitschrift fiir Phys. und Mathem., 



vol. vi. pp. 459 462. (Calendula qfficinalis, Tropceolum majus, 



minus, Lilium bulbiferum, Tagetes patula, erecta, Helianthus, 



Gorteria rigens). 



DeCandolle, Physiol. Veget., vol. vi. (?) p. 886. 



DeSaussure, Chemische Untersuchungen iiber die Vegetation, trans- 

 lated into German by Voigt. Leipzig, 1805. (CEnothera macro- 



carpa). 

 Trommsdorff's Journal de Pharmacie, vol. viii. part ii. p. 52. (Phytolacca 



decandra). 

 Schweigger's neues Journal d. Chem.u. Phys., vol. i.p. 361. (Polyanthes 



tuberosa). 

 Sennebier, Physiol. Veget., vol. iii. p. 315. (Arum maculatum in pure 



oxygen gas).* 



The giving out of light by the Rhizomorphce and from decayed vege- 

 tables seems to be owing to the presence of a peculiar substance from 

 which the light proceeds. Its nature, however, is by no means yet 

 established, and we know nothing of its chemical properties. The 

 existence of a chemical process, a kind of slow combustion, in this instance, 

 is probable, first, from its analogy with the decomposition of vegetable 

 substances in general, and also from the circumstance that this pheno- 

 menon does not always take place, but only under peculiar circumstances. 

 Meyen says " it is no chemical process, but a phenomenon of expiring 

 life, because it does not always occur." But the very reverse would 

 follow from this. When, however, he asserts in page 205 " that it is the 

 result of the most intense processes of life, or of decaying life, and 

 probably is only an intense respiration," his probable meaning becomes, 

 indeed, obscure and mystical enough. 



In spite of the number of observations enumerated, it is yet possible 

 that the giving out of light from flowers may be dependant upon an illu- 

 sion, the same as occurs in the case of the Schistostega osmundacea, a 

 small species of Moss, the proembryo of which Bridel-Brideri described 

 as Catoptridium smaragdinum, whilst the great algologist Agardh proved 

 that it was decidedly a new species of Protococcus. But it happens to be 

 neither one nor the other, but the proembryo of the Moss mentioned, as 

 Unger has proved beyond doubt. 



The giving out of light from formless fluids, as from the milky juice of 



* To this list I may add, that in the Transactions of the British Association for 

 1843, there is a notice of a " A luminous Appearance on the Common Marigold ( Ca- 

 lendula fM/r/wm*)," by Richard Dowden ; and some remarks of my own on the same 

 subject, in the Gardener's Chronicle for 1843. There are some interesting observa- 

 tions on " Phosphorescence " in Professor Matteucci's Lectures, before alluded to. 

 TRANS. 



