Societies and Academies

Abstract

LONDON. Royal Society, March 5.—Sir William Crookes, president, in the chair.—Harold Wager: The action of light on chlorophyll. When chlorophyll is decomposed by light, at least two distinct substances are formed, one of which is an aldehyde or mixture of aldehydes, and the other an active oxidising agent, capable of bringing about the liberation of iodine from potassium iodide. The decomposition of chlorophyll appears to be due directly to the action of light and is not an after effect of the photo-synthesis of carbon dioxide and water. It takes place only in the presence of oxygen, and it appears to be a case of photo-oxidation, for oxygen is used up so completely in the process that chlorophyll can be used instead of pyrogallol and caustic potash to determine the amount of oxygen in a given amount of air: In the absence of oxygen no bleaching takes place. Carbon dioxide is not necessary to the photo-decomposition of chlorophyll and is not used up in the process, even when present in considerable quantities.—C. H. Warner: Formaldehyde as an oxidation product of chlorophyll extracts.—Franklin Kidd: The controlling influence of carbon dioxide in the maturation, dormancy, and germination of seeds. Experiments are described showing that germination of seeds can be completely inhibited by carbon dioxide in the atmosphere (20–30 per cent., varying with the temperatures used). This inhibition is not accompanied by injury. The seeds germinate at once after removal from inhibitory CO2 pressures. Experiments in the field showed that this action of CO2, may actually occur in nature. If a quantity of green plant material is buried deep in the ground, seeds planted in the soil over this decaying material are inhibited in their germination by the CO2, produced beneath them. This is of agricultural significance, and the fact that in the case of mustard seeds suspension of vitality continues, even after the external CO2 has been removed, suggests an explanation of the common occurrence of dormant seeds of this plant in fields, and possibly of other natural cases of delayed germination.—J. Hammond and F. H. A. Marshall: The functional correlation between the ovaries, uterus, and mammary glands in the rabbit; with observations on the osstrous cycle.—Dr. J. F. Gaskell: The chromaffine system of annelids and the relation of this system to the contractile vascular system in the leech, Hirudo medicinalis. The possession of a chromaffine system, consisting of cells which take a yellow stain with chrome salts, is a common property of almost all members of the vertebrate kingdom. The presence of this reaction is coincident with the secretion of the pressor substance, adrenalin, and is probably dependent upon it. Even in the lowest vertebrate, Petromyzon, the system is well developed, being diffusely though segmentally arranged throughout the body. Chromaffine cells have also been observed in certain annelids by Sommet and Poll, reaching their highest development in the Hirudinea; the reaction is given by six nerve cells in each segmental ganglion. The conclusion is drawn that the contractile vascular system of vertebrates and its regulators, the chromaffine system and the sympathetic system, originally arose together in the annelid group.